/* Picat 3.0#5 */
/* Author: Hakan Kjellerstrand */
table
partition1(0) = 1.
partition1(N) = P =>
  S = 0,
  K = 1,
  M = (K*(3*K-1)) // 2,
  while (M <= N)
     S := S - ((-1)**K)*partition1(N-M),
     K := K + 1,
     M := (K*(3*K-1)) // 2
  end,
  K := 1,
  M := (K*(3*K+1)) // 2,
  while (M <= N)
     S := S - ((-1)**K)*partition1(N-M),
     K := K + 1,
     M := (K*(3*K+1)) // 2
  end,
  P = S.

Picat> time(println('p(6666)'=partition1(6666)))
p(6666) = 193655306161707661080005073394486091998480950338405932486880600467114423441282418165863

CPU time 0.206 seconds.