A059736 A class of polytopal spheres.

0, 0, 1, 0, 1, 1, 4, 6, 16, 25, 52, 89, 175, 308, 593, 1066, 2031, 3743, 7124, 13330, 25445, 48134, 92160, 175743, 337541, 647269, 1246802, 2400776, 4636319, 8955984, 17334720, 33570730, 65107971, 126355239, 245492141, 477284073

Offset

1,7

Links

Table of n, a(n) for n=1..36.

V. A. Liskovets, Some easily derivable sequences, J. Integer Sequences, 3 (2000), #00.2.2.

Formula

a(n) = A007147(n) - [n^2/12] - 1.

Maple

A016116 := n->2^floor(n/2):with(numtheory): A000016 := proc(n) local d, t1: if n = 0 then RETURN(1) else t1 := 0; for d from 1 to n do if n mod d = 0 and d mod 2 = 1 then t1 := t1+phi(d)*2^(n/ d)/(2*n); fi; od; RETURN(t1); fi; end: A007147 := n->1/2*(A016116(n-1)+A000016(n)): A059736 := n->A007147(n) - floor(n^2/12) - 1: for j from 1 to 100 do printf(`%d, `, A059736(j)) od:

Mathematica

a[n_] := (1/2)*(2^Quotient[n - 1, 2] + Total[(Mod[#, 2]*EulerPhi[#]*2^(n/#) &) /@ Divisors[n]]/(2*n)) - Floor[n^2/12] - 1;
Array[a, 36] (* Jean-François Alcover, Aug 30 2019 *)

Crossrefs

Sequence in context: A321411 A242251 A122537 * A261682 A102731 A007179

Adjacent sequences: A059733 A059734 A059735 * A059737 A059738 A059739

Keyword

nonn,easy

Author

N. J. A. Sloane, Feb 09 2001

Extensions

More terms from James A. Sellers, Feb 20 2001

Status

approved