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 A224905 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. 1
 1, 49, 91, 1117, 2929, 721, 1819, 37237, 30979, 30967, 29629, 6457, 53269, 27727, 271159, 556651, 190489, 62797, 105259, 784777, 290659, 1320829, 438037, 1019317, 333991, 248371, 226609, 671227, 384571, 1573537, 366841, 954391, 1701247, 540811, 1105291 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Pierre CAMI, Table of n, a(n) for n = 1..76 EXAMPLE 10^1+1=11 prime as 13 10^2+1=101 prime as 103 so a(1)=1. MATHEMATICA sk[n_]:=Module[{k=1}, While[!AllTrue[{10^n+k, 10^n+k+2, 10^(n+1)+k, 10^(n+1)+k+2}, PrimeQ], k++]; k]; Array[sk, 35] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 09 2020 *) PROG PFGW & SCRIPTIFY SCRIPT DIM n, 0 DIM k, -1 DIMS t OPENFILEOUT myf, a(n).txt LABEL a SET n, n+1 SET k, -1 LABEL b SET k, k+2 SETS t, %d, %d\,; n; k PRP 10^n+k, t IF ISPRP THEN GOTO c GOTO b LABEL c PRP 10^n+k+2, t IF ISPRP THEN GOTO d GOTO b LABEL d PRP 10^(n+1)+k, t IF ISPRP THEN GOTO e GOTO b LABEL e PRP 10^(n+1)+k+2, t IF ISPRP THEN GOTO f GOTO b LABEL f WRITE myf, t SET k, k+2 GOTO a CROSSREFS Cf. A124001, A224846. Sequence in context: A084632 A020176 A146064 * A224846 A260469 A275419 Adjacent sequences: A224902 A224903 A224904 * A224906 A224907 A224908 KEYWORD nonn AUTHOR Pierre CAMI, Jul 25 2013 STATUS approved

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Last modified March 24 15:16 EDT 2023. Contains 361479 sequences. (Running on oeis4.)