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A215747 a(n) = (-2)^n mod n. 3
0, 0, 1, 0, 3, 4, 5, 0, 1, 4, 9, 4, 11, 4, 7, 0, 15, 10, 17, 16, 13, 4, 21, 16, 18, 4, 1, 16, 27, 4, 29, 0, 25, 4, 17, 28, 35, 4, 31, 16, 39, 22, 41, 16, 28, 4, 45, 16, 19, 24, 43, 16, 51, 28, 12, 32, 49, 4, 57, 16, 59, 4, 55, 0, 33, 64, 65, 16, 61, 44, 69, 64, 71, 4, 7 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

n^(n+2) mod (n+2) is essentially the same.

Indices of 0's: 2^k - 1, k>=0.

Indices of 1's: A006521 except the first term.

Indices of 3's: A015940.

Indices of 5's: 7, 133, 1517, 11761, ...

a(A000040(n)) = A000040(n)-2 = A040976(n).

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..10000

EXAMPLE

a(5) = (-2)^5 mod 5 = -32 mod 5 = 3.

MAPLE

a:= n-> (-2)&^n mod n:

seq(a(n), n=1..100);  # Alois P. Heinz, Apr 08 2015

PROG

(Python)

for n in range(1, 333):

    print((-2)**n % n, end=', ')

CROSSREFS

Cf. A015910, A082493, A082494, A110146, A213381.

Sequence in context: A100649 A158962 A263824 * A246667 A199066 A306584

Adjacent sequences:  A215744 A215745 A215746 * A215748 A215749 A215750

KEYWORD

nonn,look

AUTHOR

Alex Ratushnyak, Aug 23 2012

STATUS

approved

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Last modified August 6 00:46 EDT 2021. Contains 346493 sequences. (Running on oeis4.)