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A182457
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a(0)=0, a(1)=1, a(n) = (a(n-2)*a(n-1)+1) mod n.
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2
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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
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OFFSET
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0,4
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COMMENTS
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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.
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LINKS
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MATHEMATICA
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Nest[Append[#, Mod[#[[-1]]*#[[-2]] + 1, Length[#] + 1]] &, {1, 1}, 71] (* Ivan Neretin, May 14 2015 *)
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PROG
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(Python)
prpr = 0
prev = 1
for n in range(2, 77):
. current = ( prev*prpr + 1 ) % n
. print prpr,
. prpr = prev
. prev = current
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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