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 A212488 Smallest k>0 such that (5^n-k)*5^n-1 and (5^n-k)*5^n+1 are a twin prime pair or 0 if no such k exists. 2
 0, 1, 11, 1, 17, 85, 17, 25, 71, 25, 83, 673, 3623, 1069, 401, 1225, 1361, 409, 3449, 2581, 779, 613, 605, 781, 395, 5797, 17, 6967, 755, 361, 3443, 5467, 6857, 679, 53, 9355, 3287, 2941, 22385, 6091, 8423, 685, 13649, 2437, 113, 19393, 19781, 12253, 53603, 21049, 5321, 2149, 21779 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Conjecture: There is always one such k if n>1. LINKS Pierre CAMI, Table of n, a(n) for n = 1..501 PROG (PFGW64 and SCRIPTIFY) SCRIPT DIM nn, 1 DIM kk DIM jj DIMS tt OPENFILEOUT myfile, a(n).txt OPENFILEOUT myf, b(n).txt LABEL loopn SET nn, nn+1 SET jj, 0 IF nn>500 THEN END SET kk, -1 LABEL loopk SET kk, kk+2 SETS tt, %d, %d\,; nn; kk PRP (5^nn-kk)*5^nn-1, tt IF ISPRP THEN GOTO a IF ISPRIME THEN GOTO a GOTO loopk LABEL a SET jj, jj+1 PRP (5^nn-kk)*5^nn+1, tt IF ISPRP THEN GOTO d IF ISPRIME THEN GOTO d GOTO loopk LABEL d WRITE myfile, tt SETS tt, %d, %d\,; nn; jj WRITE myf, tt GOTO loopn CROSSREFS Cf. A212487 Sequence in context: A280506 A222803 A201132 * A178243 A040131 A282868 Adjacent sequences:  A212485 A212486 A212487 * A212489 A212490 A212491 KEYWORD nonn AUTHOR Pierre CAMI, Jul 18 2012 STATUS approved

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Last modified December 6 09:25 EST 2019. Contains 329791 sequences. (Running on oeis4.)