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A346388 a(n) is the number of proper divisors of A053742(n) ending with 5. 4

%I #17 Jul 21 2021 09:18:36

%S 1,3,2,3,5,3,3,5,3,3,7,3,3,7,3,3,7,5,3,7,3,3,8,3,5,7,3,5,7,3,3,11,5,3,

%T 7,3,3,7,7,3,9,3,5,7,3,7,7,5,3,11,3,3,11,3,3,7,3,5,11,7,5,7,4,3,7,3,7,

%U 11,3,3,7,7,5,11,3,3,11,5,3,7,7,3,11,3,5

%N a(n) is the number of proper divisors of A053742(n) ending with 5.

%F a(n) = A346392(A053742(n)).

%e a(10) = 7 since there are 7 proper divisors of A053742(10) = 525 ending with 5: 5, 15, 25, 35, 75, 105 and 175.

%t a[n_]:=Length[Drop[Select[Divisors[25+50n], (Mod[#,10]==5&)], -1]]; Array[a, 90, 0]

%Y Cf. A032741, A053742, A346389 (ending with 6), A346392.

%K nonn,base

%O 0,2

%A _Stefano Spezia_, Jul 15 2021

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Last modified September 12 15:01 EDT 2024. Contains 375852 sequences. (Running on oeis4.)