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%I #59 Sep 30 2021 18:18:42
%S 1,9,25,27,49,81,121,125,169,243,289,343,361,529,625,729,841,961,1331,
%T 1369,1681,1849,2187,2197,2209,2401,2809,3125,3481,3721,4489,4913,
%U 5041,5329,6241,6561,6859,6889,7921,9409,10201,10609,11449,11881,12167,12769,14641,15625,16129,16807,17161,18769,19321,19683
%N Odd prime powers that are not primes.
%C Intersection of A061345 and A014076.
%C A014076 set minus A061346.
%H Jens Kruse Andersen, <a href="/A244623/b244623.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A079290(n) at least in the range n=3..94, and perhaps beyond. - _R. J. Mathar_, Aug 20 2014
%F Sum_{n>=1} 1/a(n) = 1/2 + Sum_{p prime} 1/(p*(p-1)) = 1/2 + A136141. - _Amiram Eldar_, Dec 21 2020
%t Join[{1},Select[Range[1,20001,2],PrimePowerQ[#]&&(!PrimeQ[#])&]] (* _Harvey P. Dale_, Dec 11 2018 *)
%o (Sage)
%o def isA244623(n) :
%o return(n % 2 == 1 and is_prime_power(n) == 1 and is_prime(n) == 0)
%o [n for n in (1..20000) if isA244623(n)]
%o (PARI) isok(p) = ((p%2) && !isprime(p) && isprimepower(p)) || (p==1); \\ _Michel Marcus_, Jul 06 2021
%Y Intersection of A005408 and A025475.
%Y Cf. A061345 (odd prime powers), A061346 (odd neither prime nor prime power), A062739 (odd powerful), A075109 (perfect powers), A136141.
%K nonn
%O 1,2
%A _Jani Melik_, Jul 02 2014
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