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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.)