A076236 a(n) = A050435(n) mod A002808(n).

1, 0, 7, 7, 8, 9, 10, 10, 10, 10, 12, 12, 12, 12, 13, 13, 13, 14, 15, 16, 16, 16, 16, 16, 17, 17, 17, 18, 19, 19, 19, 20, 20, 20, 21, 22, 22, 22, 22, 23, 23, 24, 24, 24, 24, 25, 25, 25, 25, 25, 26, 26, 27, 28, 28, 28, 30, 30, 30, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 32

Offset: 1

Author

Labos Elemer, Oct 08 2002

Keywords

• nonn

Comments

Original name: Remainder when 2nd order composite, A050435(n), is divided by first order composite, A002808(n). - Michael De Vlieger, Dec 09 2018

Examples

			Let c(n) be the n-th composite number. a(1) = 1 since c(c(1)) mod c(1) = c(4) mod 4 = 9 mod 4 = 1. a(2) = 0 since c(c(2)) mod c(2) = c(6) mod 6 = 12 mod 6 = 0. - _Michael De Vlieger_, Dec 09 2018
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A002808, A050435-A050439, A065860, A076237-A076239.

Programs

Mathematica

c[n_] := FixedPoint[n + PrimePi[#] + 1 &, n + PrimePi[n] + 1]; Array[Mod[c@ c@ #, c@ #] &, 71] (* Michael De Vlieger, Dec 09 2018, after Robert G. Wilson v at A002808 *)

Formula

a(n) = A050435(n) mod A002808(n).

Extensions

Edited by Michael De Vlieger, Dec 09 2018