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Search: id:A024966
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| A024966 |
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7 times triangular numbers. |
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+0
7
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| 0, 7, 21, 42, 70, 105, 147, 196, 252, 315, 385, 462, 546, 637, 735, 840, 952, 1071, 1197, 1330, 1470, 1617, 1771, 1932, 2100, 2275, 2457, 2646, 2842, 3045, 3255, 3472, 3696, 3927, 4165, 4410, 4662, 4921, 5187, 5460, 5740, 6027, 6321, 6622
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Except for the first term, a(n)=7*n+a(n-1), (with a(1)=7) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 24 2009]
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FORMULA
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a(n) = 7/2*n*(n+1). G.f.: A(x) = 7*x/(1-x)^3.
a(n) = (7n^2 + 7n)/2 = A000217(n)*7. [From Omar E. Pol (info(AT)polprimos.com), Dec 12 2008]
a(n)=7*n+a(n-1)-7 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 12 2009]
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EXAMPLE
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For n=2, a(2)=7*2+0-7=7; n=3, a(3)=7*3+7-7=21; n=4, a(4)=7*4+21-7=42 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 12 2009]
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MAPLE
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[seq(7*binomial(n, 2), n=1..44)]; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Nov 24 2006
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MATHEMATICA
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s=0; lst={s}; Do[s+=n++ +7; AppendTo[lst, s], {n, 0, 7!, 7}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 16 2008]
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CROSSREFS
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Cf. A028896, A033996.
Cf. A028895, A046092, A045943, A002378, A028896.
Cf. A000217. [From Omar E. Pol (info(AT)polprimos.com), Dec 12 2008]
Sequence in context: A125228 A024837 A162818 this_sequence A022602 A054569 A077354
Adjacent sequences: A024963 A024964 A024965 this_sequence A024967 A024968 A024969
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KEYWORD
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nonn,easy,new
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AUTHOR
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Joe Keane (jgk(AT)jgk.org)
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