A213013 (2^3^4^5^...^n) mod n.

0, 2, 0, 2, 2, 1, 0, 8, 2, 2, 8, 5, 8, 2, 0, 2, 8, 18, 12, 8, 2, 16, 8, 2, 18, 26, 8, 11, 2, 2, 0, 2, 2, 22, 8, 31, 18, 5, 32, 2, 8, 27, 24, 17, 16, 8, 32, 43, 2, 2, 44, 45, 26, 2, 8, 56, 40, 47, 32, 33, 2, 8, 0, 57, 2, 5, 36, 62, 22, 60, 8, 1, 68, 2, 56, 57, 44, 8, 32, 80, 2, 2, 8, 2

Offset: 2

Author

Max Alekseyev, Jun 02 2012

Keywords

• nonn

Comments

a(n) = 0 iff n is a power of 2.

Links

• Max Alekseyev, Table of n, a(n) for n = 2..1000

Crossrefs

A variant of A092188.

Programs

PARI

{ a(n,m=n,s=2) = local(g); if(s==n, return(n%m)); g=factor(gcd(s,m)); for(i=1,matsize(g)[1], g[i,2]=valuation(m,g[i,1]); m\=g[i,1]^g[i,2]); g=prod(i=1,matsize(g)[1],g[i,1]^g[i,2]); lift( chinese( Mod(0,g), Mod(s,m)^a(n,eulerphi(m),s+1) )) }