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A175265 a(1)=1. a(n) = the smallest integer > a(n-1) where |d(a(n)) - d(a(n-1))| = 1; d(n) is the number of divisors of n. 2
1, 2, 4, 5, 9, 10, 16, 18, 64, 66, 100, 102, 196, 208, 225, 230, 256, 258, 441, 442, 484, 488, 676, 678, 729, 730, 1089, 1090, 1156, 1158, 1225, 1235, 1444, 1446, 1521, 1526, 2116, 2118, 2601, 2607, 3025, 3026, 3249, 3262, 3364, 3367, 3844, 3846, 4225, 4233 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

nxt[n_]:=Module[{k=n+1}, While[Abs[DivisorSigma[0, n]-DivisorSigma[0, k]] != 1, k++]; k]; NestList[nxt, 1, 50] (* Harvey P. Dale, Oct 10 2012 *)

CROSSREFS

A175266

Sequence in context: A039891 A280729 A213011 * A320225 A070924 A266197

Adjacent sequences:  A175262 A175263 A175264 * A175266 A175267 A175268

KEYWORD

nonn

AUTHOR

Leroy Quet, Mar 18 2010

EXTENSIONS

More terms from Jon E. Schoenfield, Jun 13 2010

STATUS

approved

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Last modified October 17 16:42 EDT 2018. Contains 316286 sequences. (Running on oeis4.)