cp's OEIS Frontend

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.

%I A260826 #19 Feb 16 2025 08:33:26
%S A260826 11,13,15,18,28,578,617,2067795,843755046,134239787815,1434279786435,0
%N 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.
%C A260826 Sequence is complete, a(9) and a(10) are due to Giovanni Resta.
%H A260826 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Prime-GeneratingPolynomial.html">Prime-generating Polynomial.</a>
%e A260826 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.
%Y A260826 Cf. A050265, A092968.
%K A260826 nonn,fini,full
%O A260826 0,1
%A A260826 _Giovanni Resta_ and _Zak Seidov_, Aug 01 2015