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%I #18 Sep 05 2017 06:10:34
%S 1,3,5,7,15,17,19,27,29,31,39,41,43,51,53,74,79,85,91,106,109,115,123,
%T 129,131,141,153,159,171,173,183,205,213,219,253,259,265,287,295,301,
%U 309,311,313,319,327,335,337,343,358,389,395,397,403,411,417,419,421
%N 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.
%C a(n) - A160690(n-1) = A160689(n), for n >= 2.
%C d(A160689(n)) = d(a(n)) = A160691(n).
%H Michel Marcus, <a href="/A160690/b160690.txt">Table of n, a(n) for n = 1..5000</a>
%t 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}] (* _Farideh Firoozbakht_, May 28 2009 *)
%o (PARI) lista(nn) = {k = 1; print1(k, ", "); last = k; for (n=2, nn, k = last+1; while(numdiv(k) != numdiv(k - last), k++); print1(k, ", "); s += k; last = k;);} \\ _Michel Marcus_, Sep 05 2017
%Y Cf. A160689, A160691.
%K nonn
%O 1,2
%A _Leroy Quet_, May 24 2009
%E More terms from _Farideh Firoozbakht_, May 28 2009
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