A081730 Numbers n such that the n-th Euler number == 1 (mod n).

1, 2, 3, 4, 5, 7, 8, 11, 13, 15, 16, 17, 19, 23, 29, 31, 32, 37, 41, 43, 47, 53, 59, 61, 64, 67, 71, 73, 79, 83, 89, 91, 97, 101, 103, 107, 109, 113, 127, 128, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241

Offset

1,2

Links

Table of n, a(n) for n=1..62.

Formula

All primes, all power of 2 are in the sequence. The composites are in A035163.

Prog

(PARI) a000364(n)=subst(bernpol(2*n+1), 'x, 1/4)*4^(2*n+1)*(-1)^(n+1)/(2*n+1);
lista(nn) = {for (n=1, nn, if (Mod(a000364(n), n) == 1, print1(n, ", ")); ); } \\ Michel Marcus, Apr 18 2015

Crossrefs

Cf. A000364, A035163, A069042.

Sequence in context: A241912 A269870 A307824 * A162408 A348284 A162721

Adjacent sequences: A081727 A081728 A081729 * A081731 A081732 A081733

Keyword

nonn

Author

Benoit Cloitre, Apr 06 2003

Extensions

More terms from Weston Markham (weston.markham(AT)gmail.com), May 22 2005

Status

approved