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%I #12 Aug 18 2019 16:45:33
%S 5,7,9,11,14,21,37,38,39,57,90,97,162
%N Numbers k such that k^k + (k+1)^(k+1) is a semiprime.
%C Numbers k such that A217435(k+1) = 2.
%C a(14) >= 235, see FactorDB link.
%H FactorDB, <a href="http://factordb.com/index.php?query=236%5E236%2B235%5E235">Status of 235^235+236^236</a>.
%H Walter Nissen, <a href="http://upforthecount.com/math/nnp2.txt">Addendum to Prime factors of n^n + (n+1)^(n+1)</a>, Table F, 2014-01-07.
%e a(1) = 5 because 5^5 + 6^6 = 49781 = 67*743.
%o (PARI) for(k=0,40,if(bigomega(k^k+(k+1)^(k+1))==2,print1(k,", ")))
%Y Cf. A056187, A056788, A056790, A217435.
%K nonn,more,hard
%O 1,1
%A _Hugo Pfoertner_, Aug 15 2019