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 A102770 #28 Oct 30 2018 10:31:02 %S A102770 7,17,38,71,110,161,218,333,449,573,758,881,1010,1245,1563,1799,2043, %T A102770 2378,2591,2883,3278,3693,4316,4898,5201,5510,5831,6158,7175,8318, %U A102770 8973,9521,10355,11249,11853,12795,13610,14445,15483,16199,17285,18431,19010 %N A102770 (p*q - 1)/2 where p and q are consecutive odd primes. %C A102770 Primes in this sequence: 7, 17, 71, 449, 881, 2591, ... - _Zak Seidov_, Jan 14 2013 %H A102770 Harvey P. Dale, <a href="/A102770/b102770.txt">Table of n, a(n) for n = 1..1000</a> %F A102770 a(n) = (prime(n + 1)*prime(n + 2) - 1)/2. %F A102770 a(n) ~ 0.5 n^2/log^2 n. - _Charles R Greathouse IV_, Jan 14 2013 %F A102770 a(n) = A023515(n+2)/2. - _Jason Kimberley_, Oct 23 2015 %e A102770 a(1) = (3*5 - 1)/2 = 7. %e A102770 a(2) = (5*7 - 1)/2 = 17. %e A102770 a(3) = (7*11 - 1)/2 = 38. %t A102770 Table[(Prime[n] Prime[n + 1] - 1)/2, {n, 2, 50}] (* _Alonso del Arte_, Jan 14 2013 *) %t A102770 (Times@@#-1)/2&/@Partition[Prime[Range[2,50]],2,1] (* _Harvey P. Dale_, Apr 10 2015 *) %o A102770 (PARI) a(n)=prime(n+1)*prime(n+2)\2 \\ _Charles R Greathouse IV_, Jan 14 2013 %Y A102770 Cf. A006094, A023515, A086870, A120876. %K A102770 easy,nonn %O A102770 1,1 %A A102770 _W. Neville Holmes_, Feb 10 2005