A078160 - OEIS

%I #14 Aug 18 2024 05:17:25

%S 1,2,4,8,20,52,140,400,1203,3808,12634,43771,157821,590518,2287070,

%T 9148286,37719353,160029667,697553152,3119552536,14295585635,

%U 67052240163,321571247089,1575370942644,7876854713228,40164235888490,208699491618146,1104333907134455,5947020092025820

%N a(n) = A055086(n!).

%H Amiram Eldar, <a href="/A078160/b078160.txt">Table of n, a(n) for n = 1..807</a>

%F a(n) = A027423(n) + A078155(n). - _Amiram Eldar_, Aug 18 2024

%t Table[ Length[ Union[ Table[ Floor[w!/j], {j, 1, w!}]]], {w, 1, 11}]

%t a[n_] := Floor[Sqrt[4*n! + 1]] - 1; Array[a, 30] (* _Amiram Eldar_, Aug 18 2024 *)

%o (PARI) a(n)=sqrtint(4*n! + 1) - 1 \\ _Charles R Greathouse IV_, Mar 01 2018

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

%K nonn

%O 1,2

%A _Labos Elemer_, Nov 27 2002

%E Extended by _Robert G. Wilson v_, Dec 02 2002

%E More terms from _Charles R Greathouse IV_, Mar 01 2018

%E a(25)-a(29) from _Amiram Eldar_, Aug 18 2024