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 A335889 a(n) is the number of Mersenne primes between consecutive perfect numbers. 0
 1, 2, 0, 3, 1, 0, 0, 3, 1, 0, 0, 2, 0, 3, 2, 1, 0, 0, 0, 3, 0, 2, 1, 0, 1, 1, 2, 1, 0, 0, 4, 0, 0, 0, 2, 0, 2, 3, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..39. Chris K. Caldwell and G. L. Honaker, Jr., Prime Curio for 756839 EXAMPLE a(1) = 1 because there is exactly 1 Mersenne prime (7) between the first and second perfect numbers (6 and 28). a(4) = 3 because there are exactly 3 Mersenne primes (8191, 131071, 524287) between the fourth and fifth perfect numbers (8128 and 33550336). MATHEMATICA p = MersennePrimeExponent @ Range[47]; mer[p_] := 2^p - 1; perf[p_] := mer[p] * 2^(p - 1); mers = mer /@ p; perfs = Select[perf /@ p, # < mers[[-1]] &]; BinCounts[mers, {perfs}] (* Amiram Eldar, Jun 29 2020 *) CROSSREFS Cf. A000043, A000396, A000668. Sequence in context: A186492 A137448 A240606 * A324379 A035165 A290256 Adjacent sequences: A335886 A335887 A335888 * A335890 A335891 A335892 KEYWORD nonn,more AUTHOR G. L. Honaker, Jr., Jun 28 2020 EXTENSIONS a(5)-a(13) from Metin Sariyar, Jun 28 2020 a(14)-a(16) and a(20)-a(39) from Metin Sariyar, Jun 29 2020 a(17)-a(19) from Amiram Eldar, Jun 29 2020 STATUS approved

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Last modified July 14 20:49 EDT 2024. Contains 374323 sequences. (Running on oeis4.)