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 A187602 Primes of the form (k+1)^(k-1) + k. 2
 2, 5, 19, 1301, 262151, 4782977 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The next terms are too large to be displayed: a(7) = 159^157 + 158 (k = 158), which is 346 digits long. a(8) = 537^535 + 536 (k = 536), which is 1461 digits long. a(9) = 4671^4669 + 4670 (k = 4670), which is 17133 digits long. a(10) = 9796^9794 + 9795 (k = 9795), which is 39089 digits long. Next term has k >= 30000. LINKS Table of n, a(n) for n=1..6. EXAMPLE 1301 is in the sequence since it is prime and, using k = 5, (k+1)^(k-1) + k = 6^4 + 5 = 1296 + 5 = 1301. MATHEMATICA Do[p=(n+1)^(n-1)+n; If[PrimeQ[p], Print[p]], {n, 250}] PROG (PARI) lista(nn) = for(k=1, nn, if(ispseudoprime(q=(k+1)^(k-1)+k), print1(q, ", "))); \\ Jinyuan Wang, Mar 01 2020 CROSSREFS Cf. A238378 (corresponding k). Sequence in context: A269997 A270547 A177875 * A260140 A270556 A059079 Adjacent sequences: A187599 A187600 A187601 * A187603 A187604 A187605 KEYWORD nonn,hard AUTHOR Marco Ripà, Mar 11 2011 EXTENSIONS a(8)-a(10) from Matevz Markovic, Mar 03 2014 STATUS approved

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Last modified May 24 04:16 EDT 2024. Contains 372772 sequences. (Running on oeis4.)