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For numbers k such that A025474(k) > 1 and A025474(k+1) > 1, sequence gives A000961(k).
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%I #19 Oct 29 2023 17:31:03

%S 8,25,121,2187,32761

%N For numbers k such that A025474(k) > 1 and A025474(k+1) > 1, sequence gives A000961(k).

%C Equivalently, prime powers (either A000961 or A246655) q such that q and the next prime power are both composite numbers. - _Paolo Xausa_, Oct 25 2023

%t With[{upto=33000},Map[First,Select[Partition[Select[Range[upto],PrimePowerQ],2,1],NoneTrue[#,PrimeQ]&]]] (* _Paolo Xausa_, Oct 25 2023 *)

%Y Bisection of A068435.

%Y Cf. A000961, A025474, A246655, A366835.

%K nonn,hard,more

%O 1,1

%A _Naohiro Nomoto_, Mar 08 2002

%E Definition corrected by _Jinyuan Wang_, Sep 05 2020