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 A296420 #23 Jun 18 2019 10:53:31 %S A296420 1,10,5,10,5,2,5,10,5,10,1,10,5,10,5,2,5,10,5,10,1,10,5,10,5,2,5,10,5, %T A296420 10,1,10,5,10,5,2,5,10,5,10,1,10,5,10,5,2,5,10,5,10,1,10,5,10,5,2,5, %U A296420 10,5,10,1,10,5,10,5,2,5,10,5,10,1,10,5,10,5,2,5,10 %N A296420 Period of last digit of multiples of n. %C A296420 The list is periodic, with period 10. %e A296420 a(6)=5 because multiples of 6 are 6, 12, 18, 24, 30, 36, 42 and the last digits of those numbers are 6,2,8,4,0,6,2,... with a period of 5. %t A296420 Array[10/GCD[#, 10] &, 77] (* _Michael De Vlieger_, Dec 23 2017 *) %o A296420 (PARI) a(n) = 10/gcd(n, 10) \\ _Iain Fox_, Dec 11 2017 %Y A296420 Cf. A054531. %K A296420 base,nonn %O A296420 0,2 %A A296420 _Leonardo Sznajder_, Dec 11 2017 %E A296420 More terms from _Michael De Vlieger_, Dec 23 2017. %E A296420 Term a(0) = 1 prepended by _Halfdan Skjerning_, Jun 18 2019