A275574 ((-1)^n - 1 + 2*(n^floor((n + 1)/2)))/4.

0, 1, 4, 8, 62, 108, 1200, 2048, 29524, 50000, 885780, 1492992, 31374258, 52706752, 1281445312, 2147483648, 59293938248, 99179645184, 3065533128900, 5120000000000

Offset: 1

Author

Olivier Gérard, Aug 02 2016

Keywords

• nonn
• easy

Comments

Number of 2-r stable discrete function classes on [n] under reversal and complement to n+1.

f(n) == 2 (mod 4) if n == 5 mod 8, otherwise (except for n=2) f(n) == 0 (mod 4). - Robert Israel, Aug 09 2016

Links

• Robert Israel, Table of n, a(n) for n = 1..700

Crossrefs

Cf. A275550.

Programs

Maple

f:= n -> ((-1)^n - 1 + 2*(n^floor((n + 1)/2)))/4:
map(f, [$1..30]); # Robert Israel, Aug 09 2016

Mathematica

Table[1/4 ((-1)^ n-1+2 (n)^Floor[(n+1)/2]),{n,1,20}]