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A160690 a(1)=1. a(n) = the smallest integer > a(n-1) such that d(a(n)) = d(a(n)-a(n-1)), where d(m) = the number of divisors of m. 5
1, 3, 5, 7, 15, 17, 19, 27, 29, 31, 39, 41, 43, 51, 53, 74, 79, 85, 91, 106, 109, 115, 123, 129, 131, 141, 153, 159, 171, 173, 183, 205, 213, 219, 253, 259, 265, 287, 295, 301, 309, 311, 313, 319, 327, 335, 337, 343, 358, 389, 395, 397, 403, 411, 417, 419, 421 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A160690(n)-A160690(n-1) = A160689(n), for n >= 2. d(A160689(n)) = d(A160690(n)) = A160691(n).

LINKS

Table of n, a(n) for n=1..57.

MATHEMATICA

Contribution from Farideh Firoozbakht, May 28 2009: (Start)

a[1]=1; a[n_]:=a[n]=(For[m=a[n-1]+1, DivisorSigma[0, m]!=DivisorSigma[0, m-a[n-1]],

m++ ]; m); Table[a[n], {n, 57}] (End)

CROSSREFS

A160689, A160691

Sequence in context: A002181 A073692 A132012 * A085494 A029460 A277910

Adjacent sequences:  A160687 A160688 A160689 * A160691 A160692 A160693

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 24 20:06 EDT 2017. Contains 283993 sequences.