A341480 Number of ways to write n as an ordered sum of 3 nonprime numbers.

1, 0, 0, 3, 0, 3, 3, 3, 9, 4, 9, 12, 12, 15, 21, 19, 27, 30, 30, 39, 42, 46, 54, 60, 61, 75, 72, 91, 90, 108, 99, 129, 123, 142, 147, 168, 156, 201, 180, 217, 213, 246, 235, 279, 255, 304, 297, 336, 327, 375, 342, 412, 390, 447, 423, 492, 453, 529, 507, 573, 538, 630, 579

Offset

3,4

Links

Robert Israel, Table of n, a(n) for n = 3..10000

Formula

G.f. g(x)^3 where g(x) is the G.f. of A005171.

Maple

b:= proc(n, t) option remember;
      `if`(n=0, `if`(t=0, 1, 0), `if`(t<1, 0, add(
      `if`(isprime(j), 0, b(n-j, t-1)), j=1..n)))
    end:
a:= n-> b(n, 3):
seq(a(n), n=3..65);  # Alois P. Heinz, Feb 13 2021

Mathematica

nmax = 65; CoefficientList[Series[Sum[Boole[!PrimeQ[k]] x^k, {k, 1, nmax}]^3, {x, 0, nmax}], x] // Drop[#, 3] &

Crossrefs

Cf. A005171, A018252, A052284, A076608, A098238, A341408, A341461, A341481, A341482, A341483, A341484, A341485, A341486.

Sequence in context: A288571 A270028 A167223 * A261922 A078907 A282135

Adjacent sequences: A341477 A341478 A341479 * A341481 A341482 A341483

Keyword

nonn

Author

Ilya Gutkovskiy, Feb 13 2021

Status

approved