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 A350690 #27 Jan 05 2025 19:51:42 %S A350690 1,3,4,7,8,9,13,14,16,17,18,19,21,23,24,26,27,28,30,31,32,34,36,37,38, %T A350690 39,42,43,44,46,47,48,49,51,52,53,54,56,57,59,61,62,63,64,67,68,69,70, %U A350690 71,72,73,74,76,78,79,81,83,84,86,87,88,90,91,92,93,94,96 %N A350690 Numbers k that divide the sum of divisors of Fibonacci(k). %C A350690 This sequence is infinite (Luca, 2002). %H A350690 Amiram Eldar, <a href="/A350690/b350690.txt">Table of n, a(n) for n = 1..1197</a> %H A350690 Florian Luca, <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Scanned/40-5/advanced40-5.pdf">Problem H-590</a>, Advanced Problems and Solutions, The Fibonacci Quarterly, Vol. 40, No. 5 (2002), p. 472; <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Scanned/41-4/advanced41-4.pdf">Arithmetic Functions of Fibonacci Numbers</a>, Solution to Problem H-590 by J.-Ch. Schlage-Puchta and J. Spilker, ibid., Vol. 41, No. 4 (2002), pp. 382-384. %e A350690 3 is a term since 3 divides sigma(Fibonacci(3)) = sigma(2) = 3. %e A350690 4 is a term since 4 divides sigma(Fibonacci(4)) = sigma(3) = 4. %t A350690 Select[Range[100], Divisible[DivisorSigma[1, Fibonacci[#]], #] &] %o A350690 (Python) from sympy import divisor_sigma, fibonacci %o A350690 print([k for k in range(1, 97) if divisor_sigma(fibonacci(k)) % k == 0]) %o A350690 # _Karl-Heinz Hofmann_, Jan 12 2022 %Y A350690 Cf. A000045, A000203, A063477. %Y A350690 Similar sequences: A074698, A075775. %K A350690 nonn %O A350690 1,2 %A A350690 _Amiram Eldar_, Jan 12 2022