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A114813 Indices of Fibonacci numbers with 4 prime factors when counted with multiplicity. 3
20, 27, 28, 32, 52, 55, 74, 77, 85, 87, 93, 97, 115, 123, 143, 146, 149, 157, 161, 163, 178, 187, 197, 209, 211, 214, 215, 221, 223, 239, 242, 249, 262, 269, 283, 287, 307, 311, 313, 321, 334, 349, 379, 391, 393, 409, 421, 453, 487, 493, 499, 523, 581, 586 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

1559, 1609, 2131, 2281, 2351, 2459, 2539, 3119, 3371, 4993, 5839, 6217, 7591, 7741, 8353, 9931 are also terms (data from Kelly link). - Chai Wah Wu, Nov 11 2019

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..86

Blair Kelly, Fibonacci and Lucas Factorizations.

EXAMPLE

a(1)=20 because 20th fibonacci number(i.e. 6765) consists of 4 prime factors (i.e. 3*5*11*41)

MATHEMATICA

t = {}; Do[f = FactorInteger[Fibonacci[n]]; If[Total[Transpose[f][[2]]] == 4, AppendTo[t, n]], {n, 2, 100}]; t (* T. D. Noe, Mar 14 2014 *)

PROG

(PARI) n=1; while(n<340, if(bigomega(fibonacci(n))==4, print1(n, ", ")); n++)

CROSSREFS

Column k=4 of A303215.

Sequence in context: A219456 A248787 A070717 * A069827 A194674 A059617

Adjacent sequences:  A114810 A114811 A114812 * A114814 A114815 A114816

KEYWORD

nonn

AUTHOR

Shyam Sunder Gupta, Feb 19 2006

EXTENSIONS

More terms from Ryan Propper, May 22 2006

STATUS

approved

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Last modified December 3 22:32 EST 2021. Contains 349468 sequences. (Running on oeis4.)