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 A346392 #30 Jul 31 2021 19:50:42 %S A346392 0,0,0,0,0,0,0,0,0,0,1,1,0,0,1,0,0,0,0,1,1,1,0,1,1,0,0,0,0,1,1,1,1,0, %T A346392 1,1,0,0,0,2,1,1,0,1,2,0,0,1,0,1,1,1,0,0,1,0,0,0,0,3,1,1,1,1,1,1,0,0, %U A346392 0,1,1,2,0,0,3,0,1,0,0,3,1,1,0,2,1,0,0,1,0,2 %N A346392 a(n) is the number of proper divisors of n ending with the same digit as n. %H A346392 Michael S. Branicky, <a href="/A346392/b346392.txt">Table of n, a(n) for n = 1..10000</a> %F A346392 For a prime p, a(p) = 1 if p has the final digit equal to 1, otherwise a(p) = 0. %F A346392 a(n) = A330348(n) - 1. - _Michel Marcus_, Jul 19 2021 %e A346392 a(40) = 2 since there are 2 proper divisors of 40 ending with 0: 10 and 20. %t A346392 a[n_]:=Length[Drop[Select[Divisors[n], (Mod[#,10]==Mod[n,10]&)], -1]]; Array[a, 90] %o A346392 (PARI) a(n) = my(x = n%10); sumdiv(n, d, if (d<n, d%10 == x)); \\ _Michel Marcus_, Jul 19 2021 %o A346392 (Python) %o A346392 from sympy import divisors %o A346392 def a(n): return sum(d%10 == n%10 for d in divisors(n)[:-1]) %o A346392 print([a(n) for n in range(1, 91)]) # _Michael S. Branicky_, Jul 31 2021 %Y A346392 Cf. A010879, A032741, A330348. %K A346392 nonn,base %O A346392 1,40 %A A346392 _Stefano Spezia_, Jul 15 2021