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A014981
a(n) = c(prime(n))/prime(n), where c = Perrin sequence A001608 (starting 0,2,3,...) and prime(n) is the n-th prime.
4
1, 1, 1, 1, 2, 3, 7, 11, 28, 120, 197, 892, 2479, 4148, 11687, 56010, 271913, 461529, 2270882, 6599404, 11263855, 56250108, 164879269, 830987861, 7231032935, 21386730355, 36802336319, 109099442316, 187943217386
OFFSET
1,5
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..1000 (terms 1..200 from T. D. Noe)
Ondrej Such, An Insufficient Condition for Primality, Problem 10268, Amer. Math. Monthly, Vol. 103, No. 10 (1996), p. 911.
PROG
(PARI) c(n) = polsym(x^3-x-1, n)[n+1]; \\ A001608
a(n) = my(p=prime(n)); c(p)/p; \\ Michel Marcus, Mar 03 2022
CROSSREFS
See A001608, the main entry for the Perrin sequence.
Sequence in context: A214938 A143926 A112840 * A227885 A096362 A005479
KEYWORD
nonn,easy,nice
STATUS
approved