cp's OEIS Frontend

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.

A094516 Primes p such that q=(p^2+1)/2 is not a prime.

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%I A094516 #16 May 02 2025 10:14:23
%S A094516 2,7,13,17,23,31,37,41,43,47,53,67,73,83,89,97,103,107,109,113,127,
%T A094516 137,149,151,157,163,167,173,179,191,193,197,211,223,227,229,233,239,
%U A094516 241,251,257,263,269,277,281,283,293,307,311,313,317,331,337,347,353,359,367,373
%N A094516 Primes p such that q=(p^2+1)/2 is not a prime.
%H A094516 Ray Chandler, <a href="/A094516/b094516.txt">Table of n, a(n) for n = 1..10000</a>
%t A094516 Select[Prime[Range[100]],!PrimeQ[(#^2+1)/2]&] (* _Harvey P. Dale_, Apr 26 2017 *)
%o A094516 (Python)
%o A094516 from sympy import isprime
%o A094516 def ok(n): return (isprime(n) and (n == 2 or not isprime((n*n + 1)//2)))
%o A094516 print(*list(filter(ok, range(2, 360))), sep = ', ') # _Ya-Ping Lu_, May 01 2025
%Y A094516 Complement in primes of A048161.
%K A094516 nonn
%O A094516 1,1
%A A094516 _N. J. A. Sloane_, following a suggestion by _R. K. Guy_, Jun 05 2004