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A081727
Length of periods of Euler numbers modulo n.
2
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
COMMENTS
Terms after a(126) need more Euler numbers to check the period length. There are 85 unknown terms starting from a(127) till a(500) when 242 Euler numbers are used. - Hakan Icoz, Sep 06 2020
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
Sequence in context: A054706 A351082 A334500 * A000020 A077014 A093655
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Apr 06 2003
EXTENSIONS
More terms from Hakan Icoz, Sep 06 2020
STATUS
approved