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A023593

Exponent of least prime factor of 2*prime(n)+1.

1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 3, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 3, 1, 1, 1, 1

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OFFSET

1,6

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A067029(A072055(n)). - Amiram Eldar, Sep 22 2026

EXAMPLE

a(6) = 3 because 2*prime(6)+1 = 27 = 3^3.

MAPLE

A023593 := proc(n)

A067029(2*ithprime(n)+1) ;

end proc: # R. J. Mathar, Jul 08 2015

MATHEMATICA

Table[FactorInteger[2*Prime[n] + 1][[1]][[2]], {n, 100}] (* Clark Kimberling, Oct 01 2013 *)

PROG

(PARI) a(n) = factor(2*prime(n)+1)[1, 2]; \\ Amiram Eldar, Sep 22 2026

CROSSREFS

Cf. A067029, A072055.

Sequence in context: A366168 A016565 A051714 * A353755 A353784 A117544

Adjacent sequences: A023590 A023591 A023592 * A023594 A023595 A023596

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling

EXTENSIONS

Corrected by Clark Kimberling, Oct 01 2013

STATUS

approved