Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #16 Jul 24 2013 12:48:39
%S 1,49,91,1117,2929,3001,4831,37237,43897,54409,55669,81931,89809,
%T 194971,271159,556651,628069,639247,1036447,1615597,2075407,2086447,
%U 2414077,3331009,3442789,4088539,4178311,4330681,5834869,6846649,7928047,11222341,15520927,18575911,18615787,22426969,22645189
%N Smallest k such that (10^n+k, 10^n+k+2) and (10^(n+1)+k, 10^(n+1)+k+2) are two pairs of twin primes with k(n+1) > k(n).
%H Pierre CAMI, <a href="/A224846/b224846.txt">Table of n, a(n) for n = 1..75</a>
%e 10^1+1=11 prime as 13 10^2+1=101 prime as 103 so a(1)=1.
%t i = -1; Table[i = i + 2; While[! (PrimeQ[10^n + i] && PrimeQ[10^n + i + 2] && PrimeQ[10^(n + 1) + i] && PrimeQ[10^(n + 1) + i + 2]), i = i + 2]; i, {n, 10}] (* _T. D. Noe_, Jul 23 2013 *)
%o PFGW & SCRIPTIFY
%o SCRIPT
%o DIM n,0
%o DIM k,-1
%o DIMS t
%o OPENFILEOUT myf,a(n).txt
%o LABEL a
%o SET n,n+1
%o LABEL b
%o SET k,k+2
%o SETS t,%d,%d\,;n;k
%o PRP 10^n+k,t
%o IF ISPRP THEN GOTO c
%o GOTO b
%o LABEL c
%o PRP 10^n+k+2,t
%o IF ISPRP THEN GOTO d
%o GOTO b
%o LABEL d
%o PRP 10^(n+1)+k,t
%o IF ISPRP THEN GOTO e
%o GOTO b
%o LABEL e
%o PRP 10^(n+1)+k+2,t
%o IF ISPRP THEN GOTO f
%o GOTO b
%o LABEL f
%o WRITE myf,t
%o SET k,k+2
%o GOTO a
%Y Cf. A124001 (10^n+k and 10^n+k+2 are prime).
%K nonn
%O 1,2
%A _Pierre CAMI_, Jul 22 2013