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#18 by Michael De Vlieger at Mon Jan 16 21:41:32 EST 2023
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#17 by Jon E. Schoenfield at Mon Jan 16 21:20:53 EST 2023
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#16 by Jon E. Schoenfield at Mon Jan 16 21:20:52 EST 2023
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| NAME
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Numbers nm such that tau(nm^2) is a prime.
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| COMMENTS
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tau(nm) is the number of positive divisors of nm (A000005).
Numbers nm such that A000005(A000290(nm)) = A048691(nm) is a prime.
Supersequence of A055638 (sigma(nm^2) is prime).
See A061285(nm) = the smallest number k such that tau(k^2) = nm-th prime.
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| STATUS
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approved
editing
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#15 by Charles R Greathouse IV at Thu Sep 08 08:46:18 EDT 2022
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| PROG
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(MAGMAMagma) [n: n in [2..100000] | IsPrime(NumberOfDivisors(n^2))]
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Discussion
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| Thu Sep 08
| 08:46
| OEIS Server: https://oeis.org/edit/global/2944
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#14 by N. J. A. Sloane at Thu Mar 16 22:13:53 EDT 2017
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#13 by Robert Israel at Thu Mar 16 17:03:49 EDT 2017
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#12 by Robert Israel at Thu Mar 16 17:03:38 EDT 2017
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| LINKS
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Robert Israel, <a href="/A283262/b283262.txt">Table of n, a(n) for n = 1..10000</a>
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| MAPLE
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N:= 1000: # to get all terms <= N
es:= select(t -> isprime(2*t+1), [$1..ilog2(N)]):
Ps:= select(isprime, [2, seq(i, i=3..N, 2)]):
sort(select(`<=`, [seq(seq(p^e, e=es), p=Ps)], N)): # Robert Israel, Mar 16 2017
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approved
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#11 by N. J. A. Sloane at Thu Mar 09 14:49:10 EST 2017
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#10 by Indranil Ghosh at Thu Mar 09 14:34:30 EST 2017
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#9 by Indranil Ghosh at Thu Mar 09 14:33:51 EST 2017
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(PARI) for(n=1, 227, if(isprime(numdiv(n^2)), print1(n, ", "))) \\ Indranil Ghosh, Mar 09 2017
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approved
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