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 A346392 a(n) is the number of proper divisors of n ending with the same digit as n. 4
 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, 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, 0, 1, 1, 2, 0, 0, 3, 0, 1, 0, 0, 3, 1, 1, 0, 2, 1, 0, 0, 1, 0, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,40 LINKS Michael S. Branicky, Table of n, a(n) for n = 1..10000 FORMULA For a prime p, a(p) = 1 if p has the final digit equal to 1, otherwise a(p) = 0. a(n) = A330348(n) - 1. - Michel Marcus, Jul 19 2021 EXAMPLE a(40) = 2 since there are 2 proper divisors of 40 ending with 0: 10 and 20. MATHEMATICA a[n_]:=Length[Drop[Select[Divisors[n], (Mod[#, 10]==Mod[n, 10]&)], -1]]; Array[a, 90] PROG (PARI) a(n) = my(x = n%10); sumdiv(n, d, if (d

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Last modified January 22 13:23 EST 2022. Contains 350481 sequences. (Running on oeis4.)