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A252794
Numbers m such that 9^m + m is a semiprime.
1
1, 5, 68, 85, 86, 92, 136
OFFSET
1,2
COMMENTS
a(8) > 435. - Carl Schildkraut, Aug 14 2015
EXAMPLE
1 is in this sequence because 9^1+1 = 2*5 is semiprime.
5 is in this sequence because 9^5+5 = 2*29527 and these two factors are prime.
MATHEMATICA
Select[Range[435], PrimeOmega[9^# + #]==2 &]
PROG
(Magma) IsSemiprime:=func<i | &+[d[2]: d in Factorization(i)] eq 2>; [m: m in [1..435] | IsSemiprime(s) where s is 9^m+m];
CROSSREFS
Cf. similar sequences listed in A252788.
Cf. A252662.
Sequence in context: A207979 A129963 A115764 * A328359 A003361 A363401
KEYWORD
nonn,more
AUTHOR
Vincenzo Librandi, Dec 27 2014
EXTENSIONS
a(4)-a(7) from Carl Schildkraut, Aug 14 2015
STATUS
approved