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A092831
Indices of prime Motzkin numbers.
2
OFFSET
1,1
COMMENTS
Next term > 10^5. - Joerg Arndt, Oct 17 2016
From Serge Batalov, Feb 02 2022: (Start)
Next term (if it exists) > 2*10^7.
This sequence may be finite, for the reason that with increasing n, the density of trivially composite Motzkin numbers approaches 1. For 7*10^6 < n < 20*10^6, all Motzkin numbers have a small factor not exceeding 63809. See below.
Rowland and Yassawi, and later Burns, established asymptotic densities of A001006(n) modulo primes up to 29. In particular, the asymptotic densities of A001006(n) == 0 modulo 3, 7, 17 or 19 are 1. (End)
LINKS
E. Rowland and R. Yassawi, Automatic congruences for diagonals of rational functions, arXiv preprint arXiv:1310.8635 [math.NT], 2013-2014.
Eric Weisstein's World of Mathematics, Motzkin Number
Eric Weisstein's World of Mathematics, Integer Sequence Primes
CROSSREFS
Sequence in context: A088662 A073710 A326026 * A055257 A238366 A084068
KEYWORD
nonn,more
AUTHOR
Eric W. Weisstein, Mar 06 2004
STATUS
approved