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 A259020 #17 Apr 10 2025 21:17:52
%S A259020 1,6,10,14,26,74,94,134,146,206,314,326,386,466,576,634,674,1094,1174,
%T A259020 1294,1306,1354,1366,1546,1654,1766,1774,1894,1966,2026,2126,2174,
%U A259020 2326,2594,2654,2746,2916,2974,2986,3046,3106,3134,3136,3214,3254,3274,3314,3326
%N A259020 Numbers k such that k^2 + 1 is a divisorial prime (A258455).
%C A259020 The divisorial primes are primes of the form p = 1 + Product_{d|k} d = 1 + A007955(k) for some k.
%C A259020 Supersequence of A259021. Subsequence of A005574. First deviation from A259021 is at a(15).
%H A259020 OEIS wiki, <a href="https://oeis.org/wiki/Divisorial#Divisorial_primes">Divisorial primes</a>
%e A259020 The number 6 is in sequence because prime 37 = 6^2 + 1 is prime of the form p = 1 + Product_{d|k} d = 1 + A007955(k) for k = 6.
%o A259020 (Magma) Set(Sort([1] cat [Floor(Sqrt(&*(Divisors(n)))): n in [3..10000] | IsPrime(&*(Divisors(n))+1)]));
%Y A259020 Cf. A005574, A007955, A048943, A118369, A258455, A258897, A259021, A259023.
%K A259020 nonn
%O A259020 1,2
%A A259020 _Jaroslav Krizek_, Sep 01 2015