A078160 a(n) = A055086(n!).

1, 2, 4, 8, 20, 52, 140, 400, 1203, 3808, 12634, 43771, 157821, 590518, 2287070, 9148286, 37719353, 160029667, 697553152, 3119552536, 14295585635, 67052240163, 321571247089, 1575370942644, 7876854713228, 40164235888490, 208699491618146, 1104333907134455, 5947020092025820

Offset: 1

Author

Labos Elemer, Nov 27 2002

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..807

Crossrefs

Cf. A027423, A055086, A078155, A078159, A078161, A078162.

Programs

Mathematica

Table[ Length[ Union[ Table[ Floor[w!/j], {j, 1, w!}]]], {w, 1, 11}]
a[n_] := Floor[Sqrt[4*n! + 1]] - 1; Array[a, 30] (* Amiram Eldar, Aug 18 2024 *)

PARI

a(n)=sqrtint(4*n! + 1) - 1 \\ Charles R Greathouse IV, Mar 01 2018

Formula

a(n) = A027423(n) + A078155(n). - Amiram Eldar, Aug 18 2024

Extensions

Extended by Robert G. Wilson v, Dec 02 2002

More terms from Charles R Greathouse IV, Mar 01 2018

a(25)-a(29) from Amiram Eldar, Aug 18 2024