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A281994
Number of set partitions of [n] into subsets whose element sums are squares.
2
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
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
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Feb 04 2017
STATUS
approved