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 A120637 #10 Oct 01 2013 17:58:26 %S A120637 3,5,7,11,13,17,19,23,29,37,43,47,53,59,61,67,71,79,83,89,97,103,113, %T A120637 127,137,139,149,163,167,173,181,191,193,197,199,211,227,233,239,251, %U A120637 257,263,269,271,277,293,307,313,317,331,337,347,349,353,367,373,383 %N A120637 Primes such that their triple is 2 away from a prime number. %C A120637 This sequence is a variation of the sequence in the reference. However, this sequence should have an infinite number of terms. %D A120637 R. Crandall and C. Pomerance, Prime Numbers A Computational Perspective, Springer Verlag 2002, p. 49, exercise 1.18. %F A120637 Union of A023208 and A088878. %e A120637 19 is a prime and 19*3 = 57 which is two away from 59 which is prime. %e A120637 31 is not in the table because 31*3 = 93 which is 2 away from 91 and 95, both not prime. %t A120637 Select[Prime[Range[200]],PrimeQ[3#+2]||PrimeQ[3#-2]&] (* _Harvey P. Dale_, Aug 10 2011 *) %o A120637 (PARI) primepm2(n,k) { local(x,p1,p2,f1,f2,r); if(k%2,r=2,r=1); for(x=1,n, p1=prime(x); p2=prime(x+1); if(isprime(p1*k+r)||isprime(p1*k-r), print1(p1",") ) ) } %Y A120637 Cf. A125272. %K A120637 easy,nonn %O A120637 1,1 %A A120637 _Cino Hilliard_, Aug 17 2006