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A275574 ((-1)^n - 1 + 2*(n^floor((n + 1)/2)))/4 2
0, 1, 4, 8, 62, 108, 1200, 2048, 29524, 50000, 885780, 1492992, 31374258, 52706752, 1281445312, 2147483648, 59293938248, 99179645184, 3065533128900, 5120000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

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

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}]

CROSSREFS

Cf. A275550.

Sequence in context: A269998 A335527 A303284 * A214590 A215713 A120777

Adjacent sequences:  A275571 A275572 A275573 * A275575 A275576 A275577

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard, Aug 02 2016

STATUS

approved

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Last modified January 18 02:44 EST 2021. Contains 340249 sequences. (Running on oeis4.)