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A275381 Number of prime factors (with multiplicity) of generalized Fermat number 10^(2^n) + 1. 2
1, 1, 2, 2, 5, 4, 3, 4, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..8.

FORMULA

a(n) = A001222(A080176(n)). - Felix Fröhlich, Jul 25 2016

EXAMPLE

b(n) = 10^(2^n) + 1.

Complete Factorizations

b(0) = 11

b(1) = 101

b(2) = 73*137

b(3) = 17*5882353

b(4) = 353*449*641*1409*69857

b(5) = 19841*976193*6187457*834427406578561

b(6) = 1265011073*

       15343168188889137818369*515217525265213267447869906815873

b(7) = 257*15361*453377*P116

b(8) = 10753*8253953*9524994049*73171503617*P225

MATHEMATICA

Table[PrimeOmega[10^(2^n) + 1], {n, 0, 6}] (* Michael De Vlieger, Jul 26 2016 *)

PROG

(PARI) a(n) = bigomega(factor(10^(2^n)+1))

CROSSREFS

Cf. A072982, A080176.

Sequence in context: A217876 A209771 A209751 * A283235 A209763 A209761

Adjacent sequences:  A275378 A275379 A275380 * A275382 A275383 A275384

KEYWORD

nonn,hard,more

AUTHOR

Arkadiusz Wesolowski, Jul 25 2016

STATUS

approved

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Last modified January 29 10:34 EST 2020. Contains 331337 sequences. (Running on oeis4.)