A252741 a(n) = A252738(n) / n!

1, 2, 6, 360, 102060000, 70740876785040000000000, 4202178315558341781781575963435449520000000000000000000000000

Offset

0,2

Links

Table of n, a(n) for n=0..6.

Formula

a(n) = A252738(n) / A000142(n).

Prog

(PARI)
allocatemem(234567890);
A003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); \\ Using code of Michel Marcus
A252741print(up_to_n) = { my(s, i=0, n=0); for(n=0, up_to_n, if(0 == n, s = 1, if(1 == n, s = 2; lev = vector(1); lev[1] = 2, oldlev = lev; lev = vector(2*length(oldlev)); s = 1; for(i = 0, (2^(n-1))-1, lev[i+1] = if((i%2), A003961(oldlev[(i\2)+1]), 2*oldlev[(i\2)+1]); s *= lev[i+1]))); write("b252741.txt", n, " ", s/n!)); };
A252741print(6); \\ Produces the same terms.
(Scheme) (define (A252741 n) (/ (A252738 n) (A000142 n)))

Crossrefs

Cf. A000142, A252738, A252739, A252740.

See also comments at A005940 and A163511.

Sequence in context: A135014 A321571 A092024 * A069261 A053608 A199239

Adjacent sequences: A252738 A252739 A252740 * A252742 A252743 A252744

Keyword

nonn

Author

Antti Karttunen, Dec 21 2014

Status

approved