A056891 - OEIS

%I #6 May 13 2022 18:43:26

%S 0,1,1,2,3,5,8,11,18,23,35,38,61,69,98,107,148,138,213,226,295,311,

%T 396,377,518,539,663,686,833,717,1030,1059,1256,1289,1513,1472,1803,

%U 1843,2128,2171,2490,2328,2891,2942,3333,3389,3818,3735,4348,4413,4925,4994

%N a(n) = (s(n)-(n mod 2)) / n where s(n) is A006533.

%H Michael De Vlieger, <a href="/A056891/b056891.txt">Table of n, a(n) for n = 1..10000</a>

%e a(1) = (1-1) / 1 = 0; a(2) = (2) / 2 = 1; a(3) = (4-1) / 3 = 1; a(4) = (8) / 4 = 2; ...

%t Block[{f, g}, f[m_, n_] := Boole[Mod[n, m] == 0]; g[n_] := (n^4 - 6 n^3 + 23 n^2 - 18 n + 24)/24 + f[2, n] (-5 n^3 + 42 n^2 - 40 n - 48)/48 - f[4, n] (3 n/4) + f[6, n] (-53 n^2 + 310 n)/12 + f[12, n] (49 n/2) + f[18, n]*32 n + f[24, n]*19 n - f[30, n]*36 n - f[42, n]*50 n - f[60, n]*190 n - f[84, n]*78 n - f[90, n]*48 n - f[120, n]*78 n - f[210, n]*48 n; Array[(g[#] - Mod[#, 2])/# &, 52]] (* _Michael De Vlieger_, May 13 2022, after _T. D. Noe_ at A006533 *)

%Y Cf. A006533.

%K easy,nonn

%O 1,4

%A Tod A. Jebe (tjebe(AT)home.com), Sep 05 2000

%E More terms from _Sean A. Irvine_, May 13 2022