A275382 Number of odd prime factors (with multiplicity) of generalized Fermat number 11^(2^n) + 1.

1, 1, 1, 2, 2, 3, 2, 5, 6

Offset

0,4

Links

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

Formula

a(n) = A001222(A199592(n)) - 1 for n > 0. - Felix Fröhlich, Jul 25 2016

Example

b(n) = (11^(2^n) + 1)/2.
Complete Factorizations
b(0) = 2*3
b(1) = 61
b(2) = 7321
b(3) = 17*6304673
b(4) = 51329*447600088289
b(5) = 193*257*21283620033217629539178799361
b(6) = 316955440822738177*P49
b(7) = 15361*111489577217*574341646346402207998363393*
       4018529583345312964042058778793458689*P55
b(8) = 15190529*4696846849*19618834249745000485889*
       4393553986026616439660661873903822389581313*
       290103547098489711747952055517085778590240759297*P138

Prog

(PARI) a001222(n) = bigomega(n)
a199592(n) = 11^(2^n)+1
a(n) = if(n==0, 1, a001222(a199592(n))-1) \\ Felix Fröhlich, Jul 25 2016

Crossrefs

Cf. A199592, A273949.

Sequence in context: A318286 A214646 A340693 * A199583 A157922 A343655

Adjacent sequences: A275379 A275380 A275381 * A275383 A275384 A275385

Keyword

nonn,hard,more

Author

Arkadiusz Wesolowski, Jul 25 2016

Extensions

a(8) was found in 2006 by Bruce Dodson

Status

approved