cp's OEIS Frontend

A135283 Sum of staircase twin primes according to the rule: top + bottom + next top.

%I A135283 #5 Sep 10 2016 15:54:25
%S A135283 13,23,41,65,101,143,191,245,311,353,425,479,551,581,623,695,749,821,
%T A135283 875,971,1115,1271,1325,1445,1613,1739,1817,1877,1943,2129,2441,2471,
%U A135283 2513,2597,2783,3071,3113,3161,3215,3335,3533,3737,3845,3881,3923,4067
%N A135283 Sum of staircase twin primes according to the rule: top + bottom + next top.
%C A135283 We list the twin primes in staircase fashion as follows.
%C A135283 3
%C A135283 5_5
%C A135283 __7_11
%C A135283 ____13_17
%C A135283 _______19_29
%C A135283 __________31_41
%C A135283 _____________.._..
%C A135283 ________________tu(n)_tl(n)
%C A135283 ______________________tu(n+1)
%C A135283 ...
%C A135283 where tl(n) = n-th lower twin prime, tu(n) = n-th upper twin prime. Then a(n) = tl(n) + tu(n) + tl(n+1).
%F A135283 a(n) = A054735(n)+A001359(n+1). - _R. J. Mathar_, Sep 10 2016
%o A135283 (PARI) g(n) = for(x=1,n,y=twinu(x)+twinl(x) + twinl(x+1);print1(y",")) twinl(n) = / *The n-th lower twin prime. */ { local(c,x); c=0; x=1; while(c<n, if(ispseudoprime(prime(x)+2),c++); x++; ); return(prime(x-1)) } twinu(n) = /* The n-th upper twin prime. */ { local(c,x); c=0; x=1; while(c<n, if(isprime(prime(x)+2),c++); x++; ); return(prime(x)) }
%K A135283 nonn
%O A135283 1,1
%A A135283 _Cino Hilliard_, Dec 02 2007