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 A126017 Smallest prime of the form k^n + k^(n-1) - 1. 1
 2, 5, 11, 23, 47, 971, 191, 383, 22136835839, 1310719, 2259801991, 6143, 353563778431304822783, 91424858111, 5425784582791, 57395627, 21474836479, 1099999999999999999, 786431, 13508517176729920889 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Primes arising in A125973. LINKS EXAMPLE Consider n = 10. k^n + k^(n-1) - 1 evaluates to 1, 1535, 78731, 1310719 for k = 1, ..., 4. Only the last of these numbers, 4^10+4^9-1 = 1310719, is prime, hence a(10) = 1310719. PROG (PARI) {for(n=1, 20, k=1; while(!isprime(a=k^n+k^(n-1)-1), k++); print1(a, ", "))} - Klaus Brockhaus, Dec 17 2006 CROSSREFS Cf. A000040, A045546, A125881-A125885, A125965-A125973. Sequence in context: A007505 A246492 A059411 * A292937 A034468 A283075 Adjacent sequences:  A126014 A126015 A126016 * A126018 A126019 A126020 KEYWORD nonn AUTHOR Artur Jasinski, Dec 14 2006 EXTENSIONS Edited and extended by Klaus Brockhaus, Dec 17 2006 STATUS approved

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Last modified January 22 01:28 EST 2022. Contains 350481 sequences. (Running on oeis4.)