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 A178837 #13 Jul 15 2025 11:08:10 %S A178837 3,4,5,8,9,11,14,15,18,22,25,26,27,29,30,31,34,39,41,43,45,47,51,53, %T A178837 54,58,61,63,65,66,67,81,85,87,90,94,99,105,107,111,113,118,122,133, %U A178837 135,139,147,149,151,161,167,169,173,187,191,193,194,195,198,202,213,223 %N A178837 Indices k such that the sum of the digits of Fibonacci(k) is a prime number. %e A178837 3 is in the sequence because Fibonacci(3) = 2, and 2 is prime. %e A178837 113 is in the sequence because Fibonacci(113) = 184551825793033096366333 and the sum of the digits = 103 is prime. %p A178837 with(combinat, fibonacci):nn:= 120: for n from 1 to 700 do:p:=fibonacci(n):l:=length(p):n0:=p:s:=0:for m from 1 to l do:q:=n0:u:=irem(q, 10):v:=iquo(q, 10):n0:=v :s:=s+u:od:if type(s, prime)=true then printf(`%d, `, n): else fi:od: %p A178837 # second Maple program: %p A178837 q:= n-> isprime(add(i, i=convert(combinat[fibonacci](n), base, 10))): %p A178837 select(q, [$0..223])[]; # _Alois P. Heinz_, Jul 15 2025 %t A178837 Select[Range[300],PrimeQ[Total[IntegerDigits[Fibonacci[#]]]]&] (* _Harvey P. Dale_, Oct 22 2017 *) %Y A178837 Cf. A000045, A065398. %K A178837 nonn,base %O A178837 1,1 %A A178837 _Michel Lagneau_, Jun 17 2010