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Search: id:A064710
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| A064710 |
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Sum of divisors of n and product of divisors of n are both perfect squares. |
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+0
2
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| 1, 22, 66, 70, 81, 94, 115, 119, 170, 210, 214, 217, 265, 282, 310, 322, 343, 345, 357, 364, 382, 385, 472, 497, 510, 517, 527, 642, 651, 679, 710, 742, 745, 782, 795, 820, 862, 884, 889, 930, 935, 966, 970, 1029, 1066, 1080, 1092, 1146, 1155, 1174
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,1000
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PROGRAM
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(PARI) a(n) = n^(numdiv(n)/2) for(n=1, 2000, if(issquare(sigma(n)) && issquare(a(n)), print1(n, ", ")))
(PARI) pd(n)= { d=numdiv(n); if (d%2, round(sqrt(n))^d, n^(d/2)) } { n=0; for (m=1, 10^9, if (issquare(sigma(m)) && issquare(pd(m)), write("b064710.txt", n++, " ", m); if (n==1000, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 23 2009]
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CROSSREFS
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Cf. A007955, A000203.
Sequence in context: A124715 A126376 A136604 this_sequence A164136 A041946 A041948
Adjacent sequences: A064707 A064708 A064709 this_sequence A064711 A064712 A064713
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KEYWORD
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easy,nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Oct 13 2001
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EXTENSIONS
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Corrected by Harvey P. Dale (hpd1(AT)nyu.edu), Oct 23 2001
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