A121874 Numbers n such that Fibonacci(n) == 0 (mod triangular(n)).

1, 10, 60, 108, 180, 240, 250, 540, 600, 660, 768, 1008, 1200, 1320, 1620, 1800, 1860, 2160, 2520, 2688, 2736, 3000, 3060, 3300, 3360, 3528, 3888, 4200, 4800, 4860, 4968, 5050, 5280, 5520, 5580, 5880, 6120, 6480, 6600, 6720, 6840, 7320, 7560, 7680, 8100

Offset: 1

Author

Robert G. Wilson v, Aug 31 2006

Keywords

• nonn

Comments

Zero terms of A121343.

Links

• Giovanni Resta, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A121343, A000045, A000217.

Programs

GAP

Filtered([1..8250], n-> (Fibonacci(n) mod Binomial(n+1,2))=0 ); # G. C. Greubel, Oct 08 2019

Magma

[n: n in [1..8250] | Fibonacci(n) mod Binomial(n+1,2) eq 0]; // G. C. Greubel, Oct 08 2019

Mathematica

Select[Range@10000, Mod[Fibonacci@#, #(# + 1)/2] == 0 &]

PARI

for(n=1, 8250, if(Mod(fibonacci(n), binomial(n+1,2))==0, print1(n", "))) \\ G. C. Greubel, Oct 08 2019

Sage

[n for n in (1..8500) if Mod(fibonacci(n), binomial(n+1,2))==0] # G. C. Greubel, Oct 08 2019

Formula

Numbers n where A000045(n) == 0 (mod A000217(n)).