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 A063685 Numbers k such that !k + phi(k) - 1 is prime. 0
 2, 3, 4, 5, 11, 20, 85, 212, 4925 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(10) > 5000. - J.W.L. (Jan) Eerland, Nov 19 2022 a(10) > 13469. - J.W.L. (Jan) Eerland, Nov 20 2022 LINKS Table of n, a(n) for n=1..9. MATHEMATICA n=1; Monitor[Parallelize[While[True, If[PrimeQ[Sum[Factorial[k], {k, 0, n-1}]+EulerPhi[n]-1], Print[n]]; n++]; n], n] (* J.W.L. (Jan) Eerland, Nov 19 2022 *) PROG (PARI) f(n) = sum(k=0, n-1, k!); \\ A003422 for(n=1, 10^6, if(isprime(f(n)+eulerphi(n)-1), print(n))) CROSSREFS Cf. A003422. Sequence in context: A118968 A073528 A116067 * A006481 A118597 A083160 Adjacent sequences: A063682 A063683 A063684 * A063686 A063687 A063688 KEYWORD nonn,more AUTHOR Jason Earls, Aug 22 2001 EXTENSIONS a(9) from J.W.L. (Jan) Eerland, Nov 19 2022 STATUS approved

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Last modified February 22 18:56 EST 2024. Contains 370260 sequences. (Running on oeis4.)