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A182457 a(0)=0, a(1)=1, a(n) = (a(n-2)*a(n-1)+1) mod n. 2
0, 1, 1, 2, 3, 2, 1, 3, 4, 4, 7, 7, 2, 2, 5, 11, 8, 4, 15, 4, 1, 5, 6, 8, 1, 9, 10, 10, 17, 26, 23, 10, 7, 5, 2, 11, 23, 32, 15, 13, 36, 18, 19, 42, 7, 25, 38, 11, 35, 43, 6, 4, 25, 48, 13, 20, 37, 0, 1, 1, 2, 3, 7, 22, 27, 10, 7, 4, 29, 48, 63, 43, 46, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Indices of zeros:

0, 57, 123, 1975, 2551, 5473, 5537, 7271, 39480, 132993, 153539, 224581, 5925390, 10243877, 123259126, 284753964, 2520364708, 2985427716, 5115049972, 11066575675, 13451039887, 33557189081, 242574973569, 5212220671625, 10346718074797

Conjecture: a(n) contains infinitely many zeros.

LINKS

Ivan Neretin, Table of n, a(n) for n = 0..10000

MATHEMATICA

Nest[Append[#, Mod[#[[-1]]*#[[-2]] + 1, Length[#] + 1]] &, {1, 1}, 71] (* Ivan Neretin, May 14 2015 *)

PROG

(Python)

prpr = 0

prev = 1

for n in range(2, 77):

.  current = ( prev*prpr + 1 ) % n

.  print prpr,

.  prpr = prev

.  prev = current

CROSSREFS

Cf. A182458.

Sequence in context: A037222 A107357 A251718 * A334715 A026105 A303868

Adjacent sequences:  A182454 A182455 A182456 * A182458 A182459 A182460

KEYWORD

nonn,easy

AUTHOR

Alex Ratushnyak, Apr 30 2012

STATUS

approved

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Last modified December 8 16:05 EST 2021. Contains 349596 sequences. (Running on oeis4.)