A337811 - OEIS

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A337811

Numbers k such that the number of distinct prime factors of 2^k - 1 is less than the corresponding count for 2^k + 1.

1, 5, 7, 13, 17, 19, 25, 26, 31, 34, 35, 37, 38, 41, 46, 49, 59, 61, 62, 65, 67, 77, 78, 83, 85, 89, 91, 93, 97, 98, 103, 107, 109, 118, 122, 123, 125, 127, 131, 133, 134, 137, 139, 143, 145, 147, 149, 153, 157, 170, 173, 175, 177, 185, 186, 189, 193, 194, 195

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..59.

MATHEMATICA

Select[Range[200], PrimeNu[2^#-1]<PrimeNu[2^#+1]&] (* Harvey P. Dale, Nov 04 2023 *)

PROG

(PARI) for(n=1, 200, if(omega(2^n-1)<omega(2^n+1), print1(n, ", ")))

CROSSREFS

Cf. A046799, A046800, A067886, A337810, A337812, A337813.

Sequence in context: A092551 A177017 A136089 * A040995 A091301 A040125

Adjacent sequences: A337808 A337809 A337810 * A337812 A337813 A337814

KEYWORD

nonn

AUTHOR

Hugo Pfoertner, Sep 23 2020

STATUS

approved