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A309747
Numbers k such that k^k + (k+1)^(k+1) is a semiprime.
0
5, 7, 9, 11, 14, 21, 37, 38, 39, 57, 90, 97, 162
OFFSET
1,1
COMMENTS
Numbers k such that A217435(k+1) = 2.
a(14) >= 235, see FactorDB link.
EXAMPLE
a(1) = 5 because 5^5 + 6^6 = 49781 = 67*743.
PROG
(PARI) for(k=0, 40, if(bigomega(k^k+(k+1)^(k+1))==2, print1(k, ", ")))
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Hugo Pfoertner, Aug 15 2019
STATUS
approved