A120875 Product of twin primes minus 1.

14, 34, 142, 322, 898, 1762, 3598, 5182, 10402, 11662, 19042, 22498, 32398, 36862, 39202, 51982, 57598, 72898, 79522, 97342, 121102, 176398, 186622, 213442, 272482, 324898, 359998, 381922, 412162, 435598, 656098, 675682, 685582, 736162

Offset: 1

Author

Lekraj Beedassy, Jul 09 2006

Keywords

• nonn

Comments

This sequence is a subsequence of A023515.

Links

• Jason Kimberley (using T. Noe's b037074), Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A002822, A023515, A037074, A075369, A120876.

Programs

Mathematica

Times[#, # + 2] - 1 & /@ Select[Prime@ Range@ 150, PrimeQ[# + 2] &] (* Michael De Vlieger, Oct 23 2015 *)

PARI

for(n=1, 200, if(prime(n+1)-prime(n)==2, print1(prime(n)*prime(n+1)-1", "))) \\ Altug Alkan, Oct 23 2015

Formula

a(n) = A037074(n)-1 = (A014574(n))^2 -2 = A075369(n)-2.

a(n) = 2*A120876(n). - Jason Kimberley, Oct 23 2015

a(n) = 36*A002822(n-1)^2-2, for n>1. - Jason Kimberley, Oct 23 2015

a(n) = A023515(A107770(n)). - Jason Kimberley, Oct 23 2015