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A322547
Numbers k such that every integer partition of k contains a 1, a squarefree number, or a prime power.
2
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 21, 22, 23, 25, 26, 27, 29, 31, 33, 34, 35, 37, 39, 41, 43, 47, 49, 51, 53, 55, 59, 61, 67, 71, 79
OFFSET
1,2
EXAMPLE
48 does not belong to the sequence because there are integer partitions of 48 containing no 1's, squarefree numbers, or prime powers, namely: (48), (36,12), (28,20), (24,24), (24,12,12), (18,18,12), (12,12,12,12).
MATHEMATICA
nn=100;
ser=Product[If[PrimePowerQ[n]||SquareFreeQ[n], 1, 1/(1-x^n)], {n, nn}];
Join@@Position[CoefficientList[Series[ser, {x, 0, nn}], x], 0]-1
KEYWORD
nonn,fini,full
AUTHOR
Gus Wiseman, Dec 14 2018
STATUS
approved