A127064 a(0)=1. a(n) = a(prime(n)(mod n)) + 1, where prime(n) is the n-th prime.

1, 2, 3, 4, 5, 3, 3, 5, 5, 4, 5, 5, 3, 4, 3, 4, 4, 6, 6, 6, 6, 6, 5, 4, 7, 6, 5, 6, 5, 6, 5, 5, 5, 4, 5, 5, 6, 5, 6, 6, 5, 5, 5, 7, 7, 7, 5, 5, 6, 6, 7, 7, 6, 7, 6, 6, 7, 6, 7, 6, 6, 7, 8, 7, 7, 8, 8, 8, 9, 4, 5, 5, 6, 4, 5, 6, 5, 6, 6, 4, 5, 4, 6, 5, 5, 4, 5, 4, 7, 5, 5, 4, 7, 6, 7, 8, 5, 8, 6, 6, 6, 6, 6, 7, 7

Offset: 0

Author

Leroy Quet, Mar 21 2007

Keywords

• nonn

Examples

			The 7th prime, 17, is congruent to 3 (mod 7). So a(7) = a(3) + 1 = 4 + 1 = 5.
		

Links

• Robert Israel, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A004648, A127066.

Programs

Maple

a[0]:=1: for n from 1 to 125 do a[n]:=1+a[ithprime(n) mod n] od: seq(a[n],n=0..125); # Emeric Deutsch, Mar 25 2007

Mathematica

f[l_List] := Block[{n = Length[l]},Append[l, l[[Mod[Prime[n], n] + 1]] + 1]];Nest[f, {1}, 105] (* Ray Chandler, Mar 25 2007 *)

PARI

a(n)={k=1;if(n>0,k=a(prime(n)%n)+1);k;} \\ Jinyuan Wang, Feb 01 2019

Extensions

Extended by Ray Chandler and Emeric Deutsch, Mar 25 2007