This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A121874 #11 Sep 08 2022 08:45:27 %S A121874 1,10,60,108,180,240,250,540,600,660,768,1008,1200,1320,1620,1800, %T A121874 1860,2160,2520,2688,2736,3000,3060,3300,3360,3528,3888,4200,4800, %U A121874 4860,4968,5050,5280,5520,5580,5880,6120,6480,6600,6720,6840,7320,7560,7680,8100 %N A121874 Numbers n such that Fibonacci(n) == 0 (mod triangular(n)). %C A121874 Zero terms of A121343. %H A121874 Giovanni Resta, <a href="/A121874/b121874.txt">Table of n, a(n) for n = 1..1000</a> %F A121874 Numbers n where A000045(n) == 0 (mod A000217(n)). %t A121874 Select[Range@10000, Mod[Fibonacci@#, #(# + 1)/2] == 0 &] %o A121874 (PARI) for(n=1, 8250, if(Mod(fibonacci(n), binomial(n+1,2))==0, print1(n", "))) \\ _G. C. Greubel_, Oct 08 2019 %o A121874 (Magma) [n: n in [1..8250] | Fibonacci(n) mod Binomial(n+1,2) eq 0]; // _G. C. Greubel_, Oct 08 2019 %o A121874 (Sage) [n for n in (1..8500) if Mod(fibonacci(n), binomial(n+1,2))==0] # _G. C. Greubel_, Oct 08 2019 %o A121874 (GAP) Filtered([1..8250], n-> (Fibonacci(n) mod Binomial(n+1,2))=0 ); # _G. C. Greubel_, Oct 08 2019 %Y A121874 Cf. A121343, A000045, A000217. %K A121874 nonn %O A121874 1,2 %A A121874 _Robert G. Wilson v_, Aug 31 2006