cp's OEIS Frontend

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.

A065746 Number of divisors of squares of all true powers of primes: a(n) = A000005(A025475(n+1)^2).

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%I A065746 #8 Apr 13 2024 05:15:57
%S A065746 5,7,5,9,5,7,11,5,13,9,5,7,15,5,11,17,5,7,5,19,5,9,13,5,5,21,7,5,5,5,
%T A065746 23,15,7,5,9,5,11,5,5,25,5,7,5,5,5,17,7,5,5,27,5,5,5,5,5,7,5,9,13,5,
%U A065746 29,11,5,5,5,19,5,5,7,5,5,5,9,7,5,5,5,31,5,5,5,5,5,5,7,5,5,5,5,5,21,5,33
%N A065746 Number of divisors of squares of all true powers of primes: a(n) = A000005(A025475(n+1)^2).
%F A065746 tau(p^(2c)), where tau is the number of divisors, c > 1 and p is prime.
%e A065746 tau(p^(2c)) = 2c+1 is prime if c = (odd prime -1)/2 = 1, 2, 3, 5, 6, 8, ... = A005097.
%t A065746 DivisorSigma[0, Select[Range[60000], ! PrimeQ[#] && PrimePowerQ[#] &]^2] (* _Amiram Eldar_, Apr 13 2024 *)
%Y A065746 Cf. A000005, A025475, A065403, A065404, A065405, A005097.
%K A065746 nonn
%O A065746 1,1
%A A065746 _Labos Elemer_, Nov 16 2001
%E A065746 Name corrected by _Amiram Eldar_, Apr 13 2024