A163750 a(n) = (n-th even nonprime mod n-th prime).

0, 1, 1, 1, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126, 128, 130, 132

Offset: 1

Author

Juri-Stepan Gerasimov, Aug 03 2009

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A000040, A163300.

Programs

Maple

A163300 := proc(n) if n = 1 then 0; else for a from procname(n-1)+2 by 2 do if not isprime(a) then return(a) ; end if; end do: end if; end proc: A163750 := proc(n) A163300(n) mod ithprime(n) ; end proc: seq(A163750(n),n=1..120) ; # R. J. Mathar, Oct 10 2009

Mathematica

A087156[n_] := Mod[n, DivisorSigma[1, n]]; Table[Mod[2*A087156[n], Prime[n]], {n, 1, 50}] (* G. C. Greubel, Aug 02 2017 *)

Formula

a(n) = (A163300(n) mod A000040(n)).