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%I #11 Dec 15 2018 22:30:02
%S 0,0,0,0,0,0,1,0,0,1,0,1,1,0,0,1,2,0,1,0,0,3,0,1,1,0,2,1,0,0,3,2,0,1,
%T 0,0,3,2,0,2,0,2,1,0,2,1,2,0,3,0,0,5,0,0,1,0,2,3,2,1,1,2,0,1,0,2,5,0,
%U 0,1,2,2,3,0,0,3,2,0,1,2,0,5,0,1,3,0,4,1,0,0,1
%N a(n) is the number of positive integers of the form (n-3k)/(2k+1), 1 <= k <= (n-1)/5.
%C If n is different from 3, then a(n)=0 iff n is in A067076, i.e., 2n+3 is prime.
%t a[n_] := Length[Select[Range[Floor[(n-1)/5]], IntegerQ[(n-3#)/(2#+1)] &]]; Array[a, 100, 0] (* _Amiram Eldar_, Dec 15 2018 *)
%o (PARI) a(n) = sum(k=1, (n-1)/5, frac((n-3*k)/(2*k+1)) == 0); \\ _Michel Marcus_, Dec 15 2018
%Y Cf. A067076, A034953, A054269, A082749, A006254, A161116.
%K nonn
%O 0,17
%A _Vladimir Shevelev_, Jun 01 2009, Jun 07 2009
%E Edited by _N. J. A. Sloane_, Jun 07 2009
%E a(44) corrected and more terms from _Michel Marcus_, Dec 15 2018
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