OFFSET
1,1
LINKS
K. D. Bajpai, Table of n, a(n) for n = 1..10000
EXAMPLE
a(4) = 16: 1! + 6! = 1 + 720 = 721 = 7 * 103 which is semiprime.
a(9) = 25: 2! + 5! = 2 + 120 = 122 = 2 * 61 which is semiprime.
MAPLE
MATHEMATICA
Select[Range[200], PrimeOmega[Total[IntegerDigits[#]!]]==2&] (* Harvey P. Dale, Jul 30 2015 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
K. D. Bajpai, May 24 2014
STATUS
approved