A281994 Number of set partitions of [n] into subsets whose element sums are squares.

1, 1, 0, 0, 1, 0, 1, 1, 7, 37, 22, 264, 310, 1181, 2350, 8102, 38471, 136528, 738072, 2811383, 12163208, 45121906, 160620225, 729516611, 3962353196

Offset

0,9

Links

Table of n, a(n) for n=0..24.

Example

a(0) = 1: {}.
a(1) = 1: 1.
a(4) = 1: 1|234.
a(6) = 1: 1|2356|4.
a(7) = 1: 1|27|36|45.
a(8) = 7: 12345678, 1258|367|4, 1267|358|4, 1357|268|4, 13|268|457, 178|2356|4, 18|27|36|45.
a(10) = 22: 1|234|5678(10)|9, 1|23569|4|78(10), 1|2356|4|78(10)|9, 1|23578|4|69(10), 1|23578|4|6(10)|9, 1|23678(10)|45|9, 1|24578(10)|36|9, 1|27|34568(10)|9, 1|258(10)|3679|4, 1|258(10)|367|4|9, 1|258(10)|36|4|79, 1|259|36|4|78(10), 1|267(10)|3589|4, 1|267(10)|358|4|9, 1|2689|357(10)|4, 1|268|357(10)|4|9, 1|27|3589|4|6(10), 1|27|358|4|69(10), 1|27|358|4|6(10)|9, 1|2789(10)|36|45, 1|27|3689(10)|45, 1|27|36|4589(10).

Crossrefs

Cf. A000110, A278339, A281871.

Sequence in context: A240274 A129737 A176544 * A246603 A043374 A038478

Adjacent sequences: A281991 A281992 A281993 * A281995 A281996 A281997

Keyword

nonn

Author

Alois P. Heinz, Feb 04 2017

Status

approved