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Search: id:A145590
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| A145590 |
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a(n)=number of numbers removed in each step of Eratosthenes' sieve for 2^12 |
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+0
1
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| 2047, 682, 272, 155, 83, 65, 46, 40, 32, 25, 22, 18, 13, 11, 9, 6, 3, 2
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Number of steps in Eratosthenes' sieve for 2^n is A060967(n).
Number of primes less than 2^12 is equal = 2^12 - (sum all of numbers in this sequence) - 1 = A007053(12).
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MATHEMATICA
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f3[k_Integer?Positive, i_Integer?Positive] := Module[{f, m, r, p}, p = Transpose[{r = Range[2, i], Prime[r]}]; f[x_] := Catch[Fold[If[Mod[x, #2[[2]]] == 0, Throw[m[ #2[[1]]] = m[ #2[[1]]] + 1], #1] &, If[Mod[x, 2] == 0, Throw[m[1] = m[1] + 1]], p]]; Table[m[n] = -1, {n, i}]; f /@ Range[k]; Table[m[n], {n, i}]]; nn = 12; kk = PrimePi[Sqrt[2^nn]]; t3 = f3[2^nn, kk] (*Bob Hanlon*)
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CROSSREFS
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A006880, A122121, A145532-A145540, A145583-A145592
Sequence in context: A115553 A068264 A024021 this_sequence A038462 A001262 A141232
Adjacent sequences: A145587 A145588 A145589 this_sequence A145591 A145592 A145593
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KEYWORD
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fini,nonn
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AUTHOR
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Artur Jasinski with assistence from Bob Hanlon (grafix(AT)csl.pl), Oct 14 2008
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