A071691 Number of ways to write n as n = x!+y!+z!+t! with 0<=x<=y<=z<=t<=n.

0, 0, 0, 5, 4, 3, 2, 1, 4, 3, 2, 1, 0, 3, 2, 1, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 4, 3, 2, 1, 0, 3, 2, 1, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 3, 2, 1, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset

1,4

Comments

If a(n) > 1, a(n+1) = a(n) - 1.

Since numbers of the form n! are rare, sequence behaves quite regularly. - Lambert Klasen (lambert.klasen(AT)gmx.de), Dec 23 2004

Links

Table of n, a(n) for n=1..105.

Prog

(PARI) for(n=1, 54, print1(sum(a=0, n, sum(b=0, a, sum(c=0, b, sum(d=0, c, if(a!+b!+c!+d!-n, 0, 1))))), ", "))

Crossrefs

Sequence in context: A031016 A261302 A284803 * A319332 A031017 A266084

Adjacent sequences: A071688 A071689 A071690 * A071692 A071693 A071694

Keyword

easy,nonn

Author

Benoit Cloitre, Jun 23 2002

Extensions

More terms from Lambert Klasen (lambert.klasen(AT)gmx.de), Dec 23 2004

Status

approved