OFFSET
0,3
COMMENTS
Heegner numbers = A003173(1..9) = {1,2,3,7,11,19,43,67,163}.
LINKS
Eric Weisstein's World of Mathematics, Heegner Number
Wikipedia, Heegner number
EXAMPLE
a(10) = #{7+3, 7+2+1, 7+1+1+1, 3+3+3+1, 3+3+2+2, 3+3+2+1+1, 3+3+4x1, 3+2+2+2+1, 3+2+2+1+1+1, 3+2+5x1, 3+7x1, 5x2, 4x2+1+1, 2+2+2+4x1, 2+2+6x1, 2+8x1, 10x1} = 17;
a(11) = #{11, 7+3+1, 7+2+2, 7+2+1+1, 7+4x1, 3+3+3+2, 3+3+3+1+1, 3+3+2+2+1, 3+3+2+1+1+1, 3+3+5x1, 3+4x2, 3+2+2+2+1+1, 3+2+2+4x1, 3+2+6x1, 3+8x1, 5x2+1, 4x2+1+1+1,2+2+2+5x1, 2+2+7x1, 2+9x1, 11x1} = 21;
a(12) = #{11+1, 7+3+2, 7+3+1+1, 7+2+2+1, 7+2+1+1+1, 7+5*1, 3+3+3+3, 3+3+3+2+1, 3+3+3+1+1+1, 3+3+2+2+2, 3+3+2+2+1+1, 3+3+2+4x1, 3+3+6x1, 3+4x2+1, 3+2+2+2+1+1+1, 3+2+2+5x1, 3+2+7x1, 3+9x1, 6x2, 5x2+1+1, 4x2+4x1, 2+2+2+6x1, 2+2+8x1, 2+10x1, 12x1} = 25.
MATHEMATICA
heegnerNums = {1, 2, 3, 7, 11, 19, 43, 67, 163};
a[n_] := Length @ IntegerPartitions[n, All, heegnerNums];
Table[a[n], {n, 0, 55}] (* Jean-François Alcover, Jun 10 2019 *)
PROG
(Haskell)
a242216 = p [1, 2, 3, 7, 11, 19, 43, 67, 163] where
p _ 0 = 1
p [] _ = 0
p ks'@(k:ks) m = if m < k then 0 else p ks' (m - k) + p ks m
(Magma) [#RestrictedPartitions(n, {1, 2, 3, 7, 11, 19, 43, 67, 163}):n in [1..60]]; // Marius A. Burtea, Jun 10 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, May 07 2014
STATUS
approved