A351096 - OEIS

%I #6 Feb 03 2022 16:45:20

%S 4,6,9,10,14,15,21,22,25,26,33,34,38,39,46,49,51,55,58,62,69,74,77,82,

%T 85,86,87,91,94,95,106,111,115,118,119,121,122,123,129,133,134,141,

%U 142,143,146,155,158,159,161,166,169,178,183,185,187,194,201,202,203,206,213,214,215,218,221,226,235,247,249,253

%N Semiprimes that are the arithmetic derivative (A003415) of some number.

%o (PARI)

%o A002620(n) = ((n^2)>>2);

%o A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));

%o isA351096(n) = if(2!=bigomega(n), 0, for(k=1,A002620(n),if(A003415(k)==n,return(1))); (0));

%Y Complement of A351095 in A001358. Subsequence of A239433.

%Y Cf. A003415, A189441.

%K nonn

%O 1,1

%A _Antti Karttunen_, Feb 03 2022