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 A287533 #13 Jun 25 2017 11:55:26 %S A287533 0,1,1,2,3,5,8,13,1,14,15,9,4,13,17,10,7,17,4,1,5,6,11,17,8,5,13,18, %T A287533 11,9,0,9,9,18,7,5,12,17,9,6,15,1,16,17,13,10,3,13,16,9,5,14,19,13,12, %U A287533 5,17,2,19,1,0,1,1,2,3,5,8,13,1,14,15,9,4,13,17,10,7,17,4,1 %N A287533 Fibonacci numbers modulo 20. %C A287533 Looking at the Fibonacci numbers modulo 10 (A003893), we see their parity and what their least significant digits are in base 10. But it doesn't tell us whether the even Fibonacci numbers are further divisible by 2, nor does it tell us the congruence modulo 4 of the odd Fibonacci numbers. %C A287533 Modulo 20, the Fibonacci numbers have a period of 60. Aside from 2, 3, 5, Fibonacci primes have a least significant digit of 9, D or J in vigesimal. %H A287533 <a href="/index/Rec#order_53">Index entries for linear recurrences with constant coefficients</a>, signature (1, -1, 1, -1, 1, 0, 0, 0, 0, 0, 0, -1, 1, -1, 1, -1, 1, 0, 0, 0, 0, 0, 0, -1, 1, -1, 1, -1, 1, 0, 0, 0, 0, 0, 0, -1, 1, -1, 1, -1, 1, 0, 0, 0, 0, 0, 0, -1, 1, -1, 1, -1, 1). %t A287533 Mod[Fibonacci[Range[0, 79]], 20] %o A287533 (PARI) a(n)=fibonacci(n%60)%20 \\ _Charles R Greathouse IV_, Jun 23 2017 %Y A287533 Cf. A079343 (Fibonacci numbers modulo 4), A082116 (Fibonacci numbers modulo 5). %K A287533 nonn,easy %O A287533 0,4 %A A287533 _Alonso del Arte_, May 26 2017