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 A270475 #9 Mar 20 2016 12:58:13 %S A270475 2,3,4,6,7,22,23,42,43,66,67,82,83,102,103,126,127,162,163,166,167, %T A270475 222,223,226,227,282,283,366,367,382,383,442,443,462,463,466,467,486, %U A270475 487,502,503,522,523,546,547,586,587,606,607,642,643,646,647,682,683,726,727,786,787 %N A270475 Integers n such that A003266(n) is not divisible by n*(n+1)/2. %C A270475 This sequence contains primes dividing all Fibonacci sequences. %e A270475 6 is a term because (1*1*2*3*5*8) is not divisible by (1+2+3+4+5+6). %e A270475 5 is not a term because (1*1*2*3*5) is divisible by (1+2+3+4+5). %t A270475 nn = 800; Function[k, Select[Range@ nn, ! Divisible[k[[#]], # (# + 1)/2] &]]@ FoldList[Times, Array[Fibonacci@ # &, nn]] (* _Michael De Vlieger_, Mar 19 2016 *) %o A270475 (PARI) a(n) = prod(k=1, n, fibonacci(k)); %o A270475 for(n=1, 1e3, if(a(n) % (n*(n+1)/2) != 0, print1(n, ", "))); %Y A270475 Cf. A000040, A000057, A003266. %K A270475 nonn %O A270475 1,1 %A A270475 _Altug Alkan_, Mar 17 2016