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%I #8 Jul 05 2015 21:57:23
%S 1,2,2,2,4,4,2,4,5,4,6,4,4,8,4,4,8,6,6,8,8,4,6,8,5,12,8,4,12,8,6,8,8,
%T 8,12,10,4,12,8,8,16,8,6,12,12,8,10,8,9,14,12,8,12,16,8,16,8,4,18,8,
%U 12,16,10,8,16,16,6,16,16,8,14,12,8,20,14,12,16,8,10,16,17,8,18,16,8,20,12
%N A117726(n)/2.
%F a(4*n) = 2 * a(n). a(4*n + 1) = A045834(n). a(4*n + 2) = A005884(n). - _Michael Somos_, Jul 05 2015
%F G.f.: (Sum_{k>0} x^(k^2 + k - 1) / (1 - x^(2*k - 1))^2) / (Sum_{k>0} x^(k*(k - 1))). - _Michael Somos_, Jul 05 2015
%e G.f. = x + 2*x^2 + 2*x^3 + 2*x^4 + 4*x^5 + 4*x^6 + 2*x^7 + 4*x^8 + 5*x^9 + ...
%o (PARI) {a(n) = my(A); if( n<1, 0, n--; A = x * O(x^n); polcoeff( sum(k=1, sqrtint(4*n + 9)\2, x^(k^2 + k - 2) / (1 - x^(2*k - 1))^2, A) / sum(k=1, sqrtint(4*n + 1)\2 + 1, x^(k^2 - k), A), n))}; /* _Michael Somos_, Jul 05 2015 */
%Y Cf. A005884, A045834.
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Apr 14 2006