

A358527


Position of p in the factorization (without multiplicity) of 2^(p1)1, where p is the nth odd prime.


3



1, 2, 2, 2, 4, 3, 3, 2, 3, 4, 6, 6, 3, 2, 3, 2, 8, 4, 5, 8, 3, 2, 5, 6, 6, 3, 2, 8, 6, 6, 4, 4, 4, 3, 5, 7, 5, 2, 3, 2, 14, 4, 7, 7, 8, 9, 3, 2, 5, 5, 4, 12, 4, 4, 2, 3, 8, 7, 12, 3, 3, 6, 4, 10, 3, 9, 13, 2, 7, 7, 2, 3, 5, 8, 2, 3, 13, 10, 10, 4, 19, 4, 13, 3
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OFFSET

1,2


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..196


EXAMPLE

a(19) = 5 because the 19th odd prime is 71 and 71 is the 5th largest distinct prime factor of 2^(711)1 = 1180591620717411303423 = 3 * 11 * 31 * 43 * 71 * 127 * 281 * 86171 * 122921.


MATHEMATICA

Array[FirstPosition[FactorInteger[2^(#  1)  1], #][[1]] &[Prime[# + 1]] &, 50] (* Michael De Vlieger, Nov 27 2022 *)


PROG

(PARI) a(n) = my(p=prime(n+1), v=factor(2^(p1)1)[, 1]); vecsearch(v, p); \\ Michel Marcus, Nov 28 2022


CROSSREFS

Cf. A065091, A098102, A358699.
Sequence in context: A194319 A208609 A249030 * A257126 A050493 A331851
Adjacent sequences: A358524 A358525 A358526 * A358528 A358529 A358530


KEYWORD

nonn


AUTHOR

G. L. Honaker, Jr., Nov 20 2022


EXTENSIONS

More terms from Amiram Eldar, Nov 23 2022


STATUS

approved



