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 A120876 #35 Feb 25 2018 20:11:08 %S A120876 7,17,71,161,449,881,1799,2591,5201,5831,9521,11249,16199,18431,19601, %T A120876 25991,28799,36449,39761,48671,60551,88199,93311,106721,136241,162449, %U A120876 179999,190961,206081,217799,328049,337841,342791,368081,388961,520199,532511,551249,563921 %N A120876 (Product of twin primes - 1)/2. %C A120876 This sequence is a subsequence of A102770. %H A120876 Jason Kimberley, <a href="/A120876/b120876.txt">Table of n, a(n) for n = 1..5000</a> %F A120876 a(n) = A120875(n)/2 = A075369(n)/2-1 = A075369(n)^2/2-1. %F A120876 a(n) = 18*A002822(n-1)^2-1, for n>1. %F A120876 a(n) = A102770(A107770(n)). - _Jason Kimberley_, Nov 10 2015 %t A120876 (Times@@#-1)/2&/@Select[Partition[Prime[Range[200]], 2,1],Last[#]- First[#]== 2&] (* _Harvey P. Dale_, Jun 26 2011 *) %o A120876 (PARI) for(n=1, 200, if(prime(n+1)-prime(n)==2, print1((prime(n)*prime(n+1)-1)/2", "))) \\ _Altug Alkan_, Oct 23 2015 %o A120876 (PARI) p=2; forprime(q=3, 1e3, if(q-p==2, print1(p*q\2", ")); p=q) \\ _Charles R Greathouse IV_, Apr 01 2016 %Y A120876 Cf. The subsequence A086870. %K A120876 nonn %O A120876 1,1 %A A120876 _Lekraj Beedassy_, Jul 09 2006 %E A120876 Corrected by _T. D. Noe_, Oct 25 2006 %E A120876 Edited by _Jason Kimberley_, Oct 23 2015