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A160689 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. 5
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; text; internal format)
OFFSET

1,2

COMMENTS

sum{k=1 to n} a(k) = A160690(n). d(A160689(n)) = d(A160690(n)) = A160691(n).

LINKS

Table of n, a(n) for n=1..95.

MATHEMATICA

Contribution from Farideh Firoozbakht, 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)

CROSSREFS

A160690, A160691

Sequence in context: A121258 A087421 A132697 * A179976 A137508 A055921

Adjacent sequences:  A160686 A160687 A160688 * A160690 A160691 A160692

KEYWORD

nonn

AUTHOR

Leroy Quet, May 24 2009

EXTENSIONS

More terms from Farideh Firoozbakht, May 28 2009

STATUS

approved

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Last modified March 25 11:34 EDT 2017. Contains 284076 sequences.