A114566 Number of prime factors of A083216(n), counted with multiplicity.
4, 2, 4, 6, 3, 5, 4, 5, 2, 10, 5, 3, 3, 3, 4, 10, 5, 7, 2, 4, 5, 10, 4, 4, 2, 4, 5, 7, 3, 5, 5, 4, 3, 8, 4, 6, 4, 6, 4, 7, 5, 4, 3, 3, 4, 10, 5, 6, 4, 5, 5, 7, 3, 5, 6, 6, 4, 10, 5, 6, 7, 4, 4, 7, 5, 9, 4, 4, 5, 8, 2, 6, 6, 5, 5, 6, 4, 5, 5, 7, 3, 7, 5, 4, 6
Offset: 0
Keywords
Examples
a(0) = 4 because Wilf(0) = 20615674205555510 = 2 * 5 * 5623 * 366631232537 has 4 prime factors with multiplicity. a(1) = 2 because Wilf(1) is semiprime, namely 3794765361567513 = 3 * 1264921787189171. a(2) = 4 because Wilf(2) = 24410439567123023 = 823 * 1069 * 5779 * 4801151. a(3) = 6 because Wilf(3) = 2^3 * 1039 * 4481 * 757266563 (note that the prime factor 2 is counted 3 times). a(4) = 3 because Wilf(4) = 52615644495813559 = 983 * 2521 * 21231883913. a(5) = 5 because Wilf(5) = 80820849424504095 = 3^2 * 5 * 43 * 41767880839537.
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..336
- R. L. Graham, A Fibonacci-Like Sequence of Composite Numbers, Math. Mag. 37, 1964, pp. 322-324.
- D. E. Knuth, A Fibonacci-Like Sequence of Composite Numbers, Math. Mag. 63, 1990, pp. 21-25.
- H. S. Wilf, Letter to the Editor, Math. Mag. 63, 1990, p. 284.
- Eric Weisstein's World of Mathematics, Primefree Sequence.
Programs
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Maple
a:= n-> numtheory[bigomega]((<<0|1>, <1|1>>^n. <<20615674205555510, 3794765361567513>>)[1, 1]): seq(a(n), n=0..80); # Alois P. Heinz, Sep 20 2017
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Mathematica
PrimeOmega[LinearRecurrence[{1,1},{20615674205555510,3794765361567513},100]] (* Paolo Xausa, Nov 07 2023 *)
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PARI
A083216(n)=if(n==0, 20615674205555510, if(n==1, 3794765361567513, A083216(n-1)+A083216(n-2))); A114566(n)=bigomega(A083216(n)); for(n=0,30, print1(A114566(n),", ")) \\ R. J. Mathar, Dec 05 2007
Extensions
Corrected and extended by R. J. Mathar, Dec 05 2007
More terms from Alois P. Heinz, Sep 20 2017
Name edited by Michel Marcus, Nov 07 2023
Comments