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A171937 Forward van Eck transform of A000005.

%I A171937 #22 Oct 14 2021 15:02:35
%S A171937 0,1,2,5,2,2,4,2,16,4,2,6,4,1,6,65,2,2,4,8,1,4,6,6,24,1,6,4,2,10,6,12,
%T A171937 1,1,3,64,4,1,7,2,2,12,4,1,5,5,6,32,72,2,4,11,6,2,2,10,1,4,2,12,6,3,5,
%U A171937 665,4,4,4,7,5,8,2,12,6,3,1,16,5,10,4,32,544,3,6,6,1,1,4,14,8,6,2,6,1,1,11
%N A171937 Forward van Eck transform of A000005.
%C A171937 Least positive k such that d(n) = d(n+k), or 0 if no such k exists (d = A000005). - _Altug Alkan_, Jul 29 2016
%H A171937 Michael De Vlieger, <a href="/A171937/b171937.txt">Table of n, a(n) for n = 1..10001</a>
%H A171937 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>
%F A171937 a(n) = A079427(n) - n. - _Ridouane Oudra_, Sep 14 2021
%t A171937 {0}~Join~Array[Block[{k = 1}, While[DivisorSigma[0, #] != DivisorSigma[0, # + k], k++]; k] &, 94, 2] (* _Michael De Vlieger_, Aug 19 2021 *)
%o A171937 (PARI) a(n) = if (n==1, 0, my(m=1, nd=numdiv(n)); while(numdiv(n+m) != nd, m++); m); \\ _Michel Marcus_, Sep 14 2021
%Y A171937 Cf. A000005, A171936.
%Y A171937 Cf. A079427.
%K A171937 nonn
%O A171937 1,3
%A A171937 _N. J. A. Sloane_, Oct 24 2010