A023863 - OEIS

%I #7 Jun 12 2019 19:15:53

%S 4,6,20,25,52,59,104,119,186,211,306,338,464,502,663,715,914,981,1222,

%T 1297,1585,1667,2004,2104,2494,2615,3062,3191,3700,3854,4429,4610,

%U 5256,5466,6186,6426,7224,7477,8356,8620,9582,9878,10929,11261,12405,12774,14014,14422

%N a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2) and t = A002808 (composite numbers).

%K nonn

%O 1,1

%A _Clark Kimberling_

%E Title simplified by _Sean A. Irvine_, Jun 12 2019