A260826 - OEIS

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A260826

Let f(k)=2*k^2+11. For n=0,1,...,11, a(n) = smallest m >= 0 such that f(m-1) is composite if m>0, f(m), f(m+1), ...,f(m+n-1) are prime, and f(m+n) is composite.

11, 13, 15, 18, 28, 578, 617, 2067795, 843755046, 134239787815, 1434279786435, 0

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OFFSET

0,1

COMMENTS

Sequence is complete, a(9) and a(10) are due to Giovanni Resta.

LINKS

Table of n, a(n) for n=0..11.

Eric Weisstein's World of Mathematics, Prime-generating Polynomial.

EXAMPLE

Note that f(0), f(1), ..., f(10) are prime, while f(11) and f(12) are composite. So a(0)=11 and a(11)=0.

CROSSREFS

Cf. A050265, A092968.

Sequence in context: A179084 A375967 A124569 * A289699 A049722 A099481

Adjacent sequences: A260823 A260824 A260825 * A260827 A260828 A260829

KEYWORD

nonn,fini,full

AUTHOR

Giovanni Resta and Zak Seidov, Aug 01 2015

STATUS

approved