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Numbers whose prime factors are raised to the powers of themselves.
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%I #16 Oct 13 2020 04:38:32

%S 108,12500,84375,337500,3294172,22235661,88942644,2573571875,

%T 10294287500,69486440625,277945762500,1141246682444,7703415106497,

%U 30813660425988,891598970659375,1211500426369012,3566395882637500,8177627877990831,24073172207803125,32710511511963324

%N Numbers whose prime factors are raised to the powers of themselves.

%C Does not include A000312: Number of labeled mappings from n points to themselves (endofunctions): n^n.

%F Sum_{n>=1} 1/a(n) = Product_{p prime} (1 + 1/p^p) - Sum_{p prime} 1/p^p - 1 = 0.009354434361... - _Amiram Eldar_, Oct 13 2020

%e 108 = 2^2*3^3. 2 is raised to the power of itself and 3 is raised to the power of itself.

%t p = Drop[Subsets@Prime@Range@7, 8]; Take[ Sort[Times @@@ (p^p)], 18] (* _Robert G. Wilson v_, Jan 26 2006 *)

%Y Cf. A000312, A048102, A051674, A094289.

%K easy,nonn

%O 1,1

%A _Cino Hilliard_, Jan 25 2006

%E Corrected and extended by _Robert G. Wilson v_, Jan 26 2006

%E Offset corrected and more terms added by _Amiram Eldar_, Oct 13 2020