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 A230259 Sequence of pairs k>0 and j>1 with the smallest j and the smallest sum j+k such that (k*j^n-1)*k*j^n-1 is prime. 2
 2, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 3, 1, 3, 2, 2, 1, 2, 1, 2, 8, 3, 5, 3, 3, 4, 1, 7, 1, 5, 4, 2, 2, 2, 1, 2, 1, 4, 1, 3, 7, 3, 2, 4, 5, 4, 1, 5, 2, 3, 3, 2, 2, 6, 2, 4, 1, 15, 1, 11, 10, 2, 5, 2, 3, 7, 3, 3, 1, 3, 1, 3, 2, 2, 1, 2, 17, 2, 5, 4, 7, 3, 5, 4, 4, 2, 2, 2, 1, 2, 5, 2, 8, 2, 4, 2, 2, 2, 1, 2, 8, 7, 5, 7, 4, 4, 1, 4, 4, 2, 2, 2, 1, 2, 17, 5, 14, 7, 2, 7, 3, 14, 6, 6, 1, 6, 3, 10, 3, 4, 3, 23, 3, 7, 12, 4, 3, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Pierre CAMI, Table of n, a(n) for n = 1..4000 EXAMPLE Sequence starts with 2,2 as (2*2^1-1)*2*2^1-1=11 is prime and (1*2^1-1)*1*2^1-1 is unity. (1*2^2-1)*1*2^2-1=11 prime so the second pair is 1,2. PROG PFGW & SCRIPTIFY SCRIPT DIM n, 0 DIM j DIM k DIM ss DIMS tt OPENFILEOUT myf, a(n).txt LABEL a SET n, n+1 IF n>2000 THEN END SET ss, 2 LABEL b SET ss, ss+1 SET j, 1 LABEL c SET j, j+1 SET k, ss-j IF k<1 THEN GOTO b SETS tt, %d, %d, %d\,; n; k; j PRP (k*j^n-1)*k*j^n-1, tt IF ISPRP THEN GOTO d GOTO c LABEL d WRITE myf, tt GOTO a CROSSREFS Cf. A156051, A227903. Sequence in context: A128853 A136165 A134193 * A085030 A078377 A291454 Adjacent sequences:  A230256 A230257 A230258 * A230260 A230261 A230262 KEYWORD nonn AUTHOR Pierre CAMI, Oct 14 2013 STATUS approved

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Last modified August 8 06:27 EDT 2020. Contains 336290 sequences. (Running on oeis4.)