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A339430 Number of compositions (ordered partitions) of n into an even number of distinct squares. 2
1, 0, 0, 0, 0, 2, 0, 0, 0, 0, 2, 0, 0, 2, 0, 0, 0, 2, 0, 0, 2, 0, 0, 0, 0, 2, 2, 0, 0, 2, 24, 0, 0, 0, 2, 0, 0, 2, 0, 24, 2, 2, 0, 0, 0, 2, 24, 0, 0, 0, 26, 24, 2, 2, 24, 0, 0, 24, 2, 0, 0, 2, 24, 24, 0, 28, 24, 0, 2, 0, 24, 24, 0, 2, 26, 24, 0, 0, 72, 24, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..10000

Index entries for sequences related to compositions

Index entries for sequences related to sums of squares

EXAMPLE

a(30) = 24 because we have [16, 9, 4, 1] (24 permutations).

MAPLE

b:= proc(n, i, p) option remember; `if`(n=0, irem(1+p, 2)*p!,

     (s-> `if`(s>n, 0, b(n, i+1, p)+b(n-s, i+1, p+1)))(i^2))

    end:

a:= n-> b(n, 1, 0):

seq(a(n), n=0..100);  # Alois P. Heinz, Dec 04 2020

MATHEMATICA

b[n_, i_, p_] := b[n, i, p] = If[n == 0, Mod[1 + p, 2]*p!,

     With[{s = i^2}, If[s > n, 0, b[n, i + 1, p] +

     b[n - s, i + 1, p + 1]]]];

a[n_] := b[n, 1, 0];

a /@ Range[0, 100] (* Jean-François Alcover, Mar 09 2021, after Alois P. Heinz *)

CROSSREFS

Cf. A000290, A331844, A332305, A339366, A339418, A339431.

Sequence in context: A022882 A171919 A000089 * A051907 A178176 A093569

Adjacent sequences:  A339427 A339428 A339429 * A339431 A339432 A339433

KEYWORD

nonn,look

AUTHOR

Ilya Gutkovskiy, Dec 04 2020

STATUS

approved

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Last modified July 24 05:23 EDT 2021. Contains 346273 sequences. (Running on oeis4.)