A085803 - OEIS

%I #13 Sep 18 2024 15:01:14

%S 15,34,35,51,57,74,91,95,121,122,123,129,134,142,143,155,161,169,183,

%T 209,213,214,218,219,221,235,237,247,253,265,274,291,299,301,305,314,

%U 319,321,323,326,327,329,334,341,361,362,381,382,391,394,395,403,407

%N Semiprimes whose digits squared sum to a semiprime.

%H Harvey P. Dale, <a href="/A085803/b085803.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[500],PrimeOmega[#]==PrimeOmega[Total[IntegerDigits[#]^2]] == 2&] (* _Harvey P. Dale_, Oct 03 2012 *)

%o (PARI) isok(k)={bigomega(k)==2 && bigomega(norml2(digits(k)))==2} \\ _Andrew Howroyd_, Sep 18 2024

%Y Intersection of A001358 and A217907.

%K base,nonn

%O 1,1

%A _Jason Earls_, Jul 24 2003

%E Offset changed by _Andrew Howroyd_, Sep 18 2024