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 A070689 #30 Feb 10 2022 15:26:59 %S A070689 1,2,4,6,10,16,36,40,66,126,130,150,156,180,210,240,250,256,270,280, %T A070689 306,396,400,420,430,466,490,556,570,576,646,690,700,750,760,826,906, %U A070689 910,936,946,966,1060,1096,1150,1276,1290,1306,1320,1366,1566,1570 %N A070689 Numbers k such that k+1 and k^2+1 are primes. %C A070689 For any n > 1 in this sequence, (n+1)*(n^2+1) has the same nonzero digits as its prime factors in base n. - _Ely Golden_, Dec 12 2016 %H A070689 Amiram Eldar, <a href="/A070689/b070689.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Zak Seidov) %t A070689 Select[ Range[2000], PrimeQ[ # + 1] && PrimeQ[ #^2 + 1] & ] %t A070689 Select[Prime[Range[250]],PrimeQ[(#-1)^2+1]&]-1 (* _Harvey P. Dale_, Feb 10 2022 *) %o A070689 (PARI) list(lim)=my(v=List()); forprime(p=2,lim+1, if(isprime(1+(p-1)^2), listput(v,p-1))); Vec(v) \\ _Charles R Greathouse IV_, Dec 13 2016 %Y A070689 Cf. A067720. %K A070689 nonn %O A070689 1,2 %A A070689 _Robert G. Wilson v_, May 13 2002