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 A205236 Least prime p > 3 such that 2^n + p*2^k - 1 is prime for some k with n/3 < k < n+1 4
 5, 5, 5, 7, 5, 5, 5, 7, 5, 5, 5, 11, 5, 5, 5, 7, 5, 5, 5, 7, 5, 5, 5, 11, 5, 5, 5, 7, 5, 5, 5, 7, 5, 5, 5, 11, 5, 5, 5, 7, 5, 5, 5, 7, 5, 5, 13, 11, 5, 5, 5, 7, 5, 5, 5, 7, 5, 5, 11, 17, 7, 5, 5, 7, 5, 5, 5, 7, 5, 5, 5, 11, 7, 5, 5, 7, 5, 5, 7, 7, 11, 5, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The prime p seems to be < 31. LINKS Pierre CAMI, Table of n, a(n) for n = 1..10800 EXAMPLE 2^1+5*2^1-1=11 prime so p=5 for n=1. 2^2+5*2^2-1=23 prime so p=5 for n=2. 2^3+5*2^3-1=47 prime so p=5 for n=3. PROG PFGW64 from Primeform group and SCRIPTIFY Command : pfgw64 -f in.txt in.txt file : SCRIPT DIM nn, 0 DIM mm DIM kk DIMS tt OPENFILEOUT myfile, prem.txt LABEL loopn SET nn, nn+1 IF nn>10800 THEN END SET kk, 2 LABEL loopk SET kk, kk+1 SET mm, nn/3 LABEL loopm SET mm, mm+1 IF mm>nn THEN GOTO loopk SETS tt, %d, %d, %d\ ; nn; p(kk); mm PRP 2^nn+p(kk)*2^mm-1, tt IF ISPRIME THEN GOTO a IF ISPRP THEN GOTO a GOTO loopm LABEL a WRITE myfile, tt GOTO loopn CROSSREFS Cf. A205237. Sequence in context: A092279 A159002 A127934 * A266948 A176172 A204911 Adjacent sequences:  A205233 A205234 A205235 * A205237 A205238 A205239 KEYWORD nonn AUTHOR Pierre CAMI, Jan 24 2012 STATUS approved

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Last modified September 27 04:10 EDT 2021. Contains 347673 sequences. (Running on oeis4.)