This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A273770 #48 Aug 08 2025 14:20:57
%S A273770 40,39,38,37,36,35,34,33,32,31,30,29,28,27,26,25,24,23,22,21,20,19,18,
%T A273770 17,16,15,14,13,13,12,11,10,11,12,11,12,12,13,12,12,13,16,17,16,15,14,
%U A273770 13,13,12,11,12,13,13,14,13,13,13,12,13,14,13,14,15,14,14,13,14,14,13
%N A273770 Max { min { x >= 0 | p + (2*n+1)*x + x^2 is composite }, p < 10^(5+n/10) }.
%C A273770 The values for p are given in A273756 which is the main entry, see there for further information and (cross)references.
%C A273770 From the initial values, the sequence seems strictly decreasing, with a(n) = 40-n, however, this property does not persist beyond a(27) = 13.
%C A273770 The upper limit on p ensures that we have a well-defined sequence: The prime k-tuple conjecture predicts existence of arbitrarily long sequences of primes of the given form, and thus unbounded minimal value of x. However, the corresponding prime tuples are expected to appear for much larger values of p. The given limit should be understood as "below the first/next such prime tuple", and in general the values a(n) should not change if that limit would be increased by some orders of magnitude. There might be counterexamples, which would be interesting. The given limit was chosen for lack of a more natural expression, and is relatively small. It could be replaced by a more appropriate function of n if a proposal is available, which should not affect the values given so far. - _M. F. Hasler_, Jan 22 2018, edited Feb 17 2020
%H A273770 M. F. Hasler, <a href="/A273770/b273770.txt">Table of n, a(n) for n = 0..100</a> (using A273756(0..100) from Don Reble), Feb 17 2020
%H A273770 <a href="/index/Pri">Index to sequences related to primes produced by polynomials</a>.
%F A273770 a(n) = 40 - n for 0 <= n <= 27.
%o A273770 (PARI) {A273770(n, p=2*n+1, L=10^(5+n/10), m)=forprime(q=1,L, for(x=1,oo, ispseudoprime(q+p*x+x^2) || (x>m && !m=x) || break));m}
%Y A273770 Cf. A273595, A273756.
%Y A273770 Cf. also A002837, A007634, A005846, A097823, A144051, A187057 ... A187060, A190800, A191456 ff.
%K A273770 nonn
%O A273770 0,1
%A A273770 _M. F. Hasler_, May 26 2016
%E A273770 Corrected and extended by _Don Reble_, Feb 15 2018