A081727 Length of periods of Euler numbers modulo n.

1, 1, 2, 1, 2, 2, 6, 4, 6, 2, 10, 2, 6, 6, 2, 8, 8, 6, 18, 2, 6, 10, 22, 4, 10, 6, 18, 6, 14, 2, 30, 16, 10, 8, 6, 6, 18, 18, 6, 4, 20, 6, 42, 10, 6, 22, 46, 8, 42, 10, 8, 6, 26, 18, 10, 12, 18, 14, 58, 2, 30, 30, 6, 32, 6, 10, 66, 8, 22, 6, 70, 12, 36, 18, 10

Offset

1,3

Links

Sean A. Irvine, Table of n, a(n) for n = 1..500 (terms 1..125 from Hakan Icoz)

Formula

a(n) = n-1 if n=2, 3, 7, 11, 19, 23, 31...is a prime == 2 or 3 (mod 4) (A045326).

Example

A000364 modulo 5 gives : 1,1,0,1,0,1,0,1,0,1,0,... with period (1,0) of length 2, hence a(5)=2.

Crossrefs

Cf. A000364, A045326.

Sequence in context: A054706 A351082 A334500 * A000020 A077014 A093655

Adjacent sequences: A081724 A081725 A081726 * A081728 A081729 A081730

Keyword

nonn

Author

Benoit Cloitre, Apr 06 2003

Extensions

More terms from Hakan Icoz, Sep 06 2020

Status

approved