A061108 Compute Euler totient function for the prime(n+1)-prime(n)-1 composite numbers between two consecutive primes; choose the largest.

2, 2, 6, 4, 8, 6, 12, 20, 8, 24, 24, 12, 24, 42, 40, 16, 48, 44, 24, 60, 54, 64, 72, 60, 32, 52, 36, 72, 110, 84, 108, 44, 120, 40, 120, 132, 82, 156, 120, 48, 160, 64, 96, 60, 180, 192, 120, 72, 120, 184, 64, 216, 220, 216, 208, 72, 200, 180, 92, 272, 264, 204, 96

Offset: 2

Author

Labos Elemer, May 29 2001

Keywords

• nonn

Links

• Harry J. Smith, Table of n, a(n) for n = 2..1000

Crossrefs

Cf. A000010, A061106.

Programs

PARI

{ n=1; q=3; forprime (p=5, prime(1003), a=0; for (i=q + 1, p - 1, a=max(eulerphi(i), a)); q=p; write("b061108.txt", n++, " ", a) ) } \\ Harry J. Smith, Jul 18 2009

Formula

a(n) = Max{phi(c); prime(n) < c < prime(n+1)}.

Extensions

Offset corrected by Michel Marcus, Mar 21 2018