OFFSET
3,6
LINKS
Alois P. Heinz, Table of n, a(n) for n = 3..10000
FORMULA
MAPLE
b:= proc(n, i) option remember; series(`if`(n=0, 1,
`if`(i<0, 0, (p-> `if`(p>n, 0, x*b(n-p, i-1)))(
`if`(i=0, 1, ithprime(i)))+b(n, i-1))), x, 3)
end:
a:= n-> coeff(b(n, numtheory[pi](n)), x, 2):
seq(a(n), n=3..96); # Alois P. Heinz, Feb 24 2021
MATHEMATICA
a[n_] := Select[IntegerPartitions[n, {2}, Join[{1},
Prime[Range[PrimePi[n-1]]]]], #[[1]] != #[[2]]&] // Length;
a /@ Range[3, 100] (* Jean-François Alcover, Jul 13 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 24 2021
STATUS
approved