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A182458 a(0)=1, a(1)=2, a(n) = (a(n-2)*a(n-1)+1) mod n. 4
1, 2, 1, 0, 1, 1, 2, 3, 7, 4, 9, 4, 1, 5, 6, 1, 7, 8, 3, 6, 19, 10, 15, 13, 4, 3, 13, 13, 2, 27, 25, 25, 18, 22, 23, 17, 32, 27, 29, 4, 37, 26, 39, 26, 3, 34, 11, 46, 27, 18, 37, 4, 45, 22, 19, 34, 31, 29, 30, 45, 31, 54, 1, 55, 56, 26, 5, 64, 49, 32, 29, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Indices of zeros: 3, 284, 295, 1042, 1478, 36382, 52328, 63463, 1564027, 19758967, 152380267, 503372464, 9766438965, 119068745443, 220054053597, 234739914603, 881852361961, 3491882402381, 3681101616539, 5880347601791, 7363426715439, 10328374852578.

Conjecture: a(n) contains infinitely many zeros.

a(A182472(n)) = n and a(m) <> n for m < A182472(n). [Reinhard Zumkeller, May 01 2012]

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

MATHEMATICA

nxt[{n_, a_, b_}]:={n+1, b, Mod[a b+1, n+1]}; Join[{1}, Rest[NestList[nxt, {1, 2, 2}, 80][[All, 2]]]] (* Harvey P. Dale, Feb 14 2019 *)

PROG

(Python)

prpr = 1

prev = 2

for n in range(2, 77):

    current = ( prev*prpr + 1 ) % n

    print(prpr, end=', ')

    prpr = prev

    prev = current

(Haskell)

a182458 n = a182458_list !! n

a182458_list = 1 : 2 : zipWith mod

   (map (+ 1) $ zipWith (*) a182458_list (tail a182458_list)) [2..]

-- Reinhard Zumkeller, May 01 2012

CROSSREFS

Cf. A182457.

Sequence in context: A269941 A035440 A029878 * A238093 A238095 A240608

Adjacent sequences:  A182455 A182456 A182457 * A182459 A182460 A182461

KEYWORD

nonn,easy

AUTHOR

Alex Ratushnyak, Apr 30 2012

STATUS

approved

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Last modified October 27 13:45 EDT 2021. Contains 348276 sequences. (Running on oeis4.)