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A160689
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a(1)=1. a(n) = the smallest positive integer such that d(a(n)) = d(sum{k=1 to n} a(k)), where d(m) = the number of divisors of m.
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5
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1, 2, 2, 2, 8, 2, 2, 8, 2, 2, 8, 2, 2, 8, 2, 21, 5, 6, 6, 15, 3, 6, 8, 6, 2, 10, 12, 6, 12, 2, 10, 22, 8, 6, 34, 6, 6, 22, 8, 6, 8, 2, 2, 6, 8, 8, 2, 6, 15, 31, 6, 2, 6, 8, 6, 2, 2, 6, 10, 2, 6, 6, 15, 13, 6, 2, 6, 8, 2, 8, 6, 10, 6, 10, 8, 8, 6, 8, 6, 10, 8, 2, 2, 10, 2, 10, 6, 2, 38, 10, 6, 10, 8, 10, 8
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| sum{k=1 to n} a(k) = A160690(n). d(A160689(n)) = d(A160690(n)) = A160691(n).
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MATHEMATICA
| Contribution from Farideh Firoozbakht (mymontain(AT)yahoo.com), May 28 2009: (Start)
a[1]=1; a[n_]:=a[n]=(s=Sum[a[k], {k, n-1}]; For[m=1, DivisorSigma[0, m]!=
DivisorSigma[0, s+m], m++ ]; m); Table[a[n], {n, 95}] (End)
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CROSSREFS
| A160690, A160691
Sequence in context: A121258 A087421 A132697 * A179976 A137508 A055921
Adjacent sequences: A160686 A160687 A160688 * A160690 A160691 A160692
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet, May 24 2009
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EXTENSIONS
| More terms from Farideh Firoozbakht (mymontain(AT)yahoo.com), May 28 2009
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