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 A225392 Numbers b such that b^(2^n) + 2 is prime for n from 0 to 4. 0
 22155, 1864149, 2760681, 6222765, 22687797, 25631319, 29309589, 33333069, 36490905, 56310891, 60212889, 74097849, 76008207, 80864685, 84214395, 132006225, 132621171, 137362521, 138993381, 152223885, 154185525, 175950081, 188261481, 188677335, 194279955 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Generalized Fermat numbers of the form b^(2^n) + k with k = 2 here. For b = 2760681, b^(2^n) + 2 is prime for n from 0 to 5 LINKS Table of n, a(n) for n=1..25. PROG (PARI) k=2; forstep(b=1, 5*10^7, [4, 2, 2, 2], i=0; for(n=0, 4, m=b^2^n+k; if(isprime(m), i++; if(i>4, print([b, m, n, i]))))) CROSSREFS Cf. A070694, A225321 Sequence in context: A043590 A043815 A157622 * A225998 A209396 A210295 Adjacent sequences: A225389 A225390 A225391 * A225393 A225394 A225395 KEYWORD nonn AUTHOR Robin Garcia, May 06 2013 EXTENSIONS a(10)-a(25) from Giovanni Resta, May 06 2013 STATUS approved

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Last modified June 16 07:19 EDT 2024. Contains 373423 sequences. (Running on oeis4.)