%I #10 Aug 27 2018 01:53:31
%S 1,2,3,4,5,8,11,16,17,31,32,41,59,64,67,83,109,127,128,157,179,191,
%T 211,241,256,277,283,331,353,367,401,431,461,509,512,547,563,587,599,
%U 617,709,739,773,797,859,877,919,967,991,1024,1031,1063,1087,1153,1171
%N One, powers of 2, and prime numbers of prime index.
%H Andrew Howroyd, <a href="/A302592/b302592.txt">Table of n, a(n) for n = 1..1000</a>
%F Union of A000079 and A006450. - _Andrew Howroyd_, Aug 26 2018
%e Entry A302242 describes a correspondence between positive integers and multiset multisystems. In this case it gives the following sequence of set multisystems.
%e 001: {}
%e 002: {{}}
%e 003: {{1}}
%e 004: {{},{}}
%e 005: {{2}}
%e 008: {{},{},{}}
%e 011: {{3}}
%e 016: {{},{},{},{}}
%e 017: {{4}}
%e 031: {{5}}
%e 032: {{},{},{},{},{}}
%e 041: {{6}}
%e 059: {{7}}
%e 064: {{},{},{},{},{},{}}
%e 067: {{8}}
%e 083: {{9}}
%e 109: {{10}}
%e 127: {{11}}
%e 128: {{},{},{},{},{},{},{}}
%t primeMS[n_]:=If[n===1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
%t Select[Range[1000],Or[#===1,Union[primeMS[#]]==={1},PrimeQ[#]&&PrimeQ[PrimePi[#]]]&]
%o (PARI) ok(n)={n>>valuation(n,2) == 1 || (isprime(n) && isprime(primepi(n)))} \\ _Andrew Howroyd_, Aug 26 2018
%Y Cf. A000961, A001222, A003963, A005117, A006450, A007716, A056239, A076610, A275024, A279791, A281113, A296133, A301765, A302242, A302243.
%K nonn
%O 1,2
%A _Gus Wiseman_, Apr 10 2018
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