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 A130638 a(n) = 1 iff d(n) = d(n+1), otherwise a(n)=0, where d(n) is the number of divisors of n, A000005. 1
 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Antti Karttunen, Table of n, a(n) for n = 1..10000 MATHEMATICA Table[If[Length[Divisors[n]] == Length[Divisors[n + 1]], 1, 0], {n, 1, 80}] (* Stefan Steinerberger, Aug 12 2007 *) PROG (PARI) A130638(n) = (numdiv(n)==numdiv(n+1)); \\ Antti Karttunen, Oct 04 2017 CROSSREFS Characteristic function of A005237. Cf. A000005. Sequence in context: A084928 A033683 A216284 * A030217 A030215 A098108 Adjacent sequences:  A130635 A130636 A130637 * A130639 A130640 A130641 KEYWORD nonn AUTHOR Giovanni Teofilatto, Aug 11 2007 EXTENSIONS Corrected and extended by Stefan Steinerberger, Aug 12 2007 More terms (up to a(105)) from Antti Karttunen, Oct 04 2017 STATUS approved

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