%I #5 Oct 17 2021 21:17:56

%S 1,3,5,10,13,21,25,36,49,64,71,89,97,118,141,166,177,205,217,248,281,

%T 316,331,369,409,451,495,541,561,610,631,683,737,793,851,911,937,1000,

%U 1065,1132,1161,1231,1261,1334,1409,1486,1519,1599,1681,1765,1851,1939,1977,2068

%N a(n) = n + (n - 1) * (n - pi(n)).

%C For all 1 <= k <= n, add 1 if k is prime, otherwise add n. For example, when n = 7, there are 4 numbers less than or equal to 7 that are prime and 3 that are not. Then a(7) = 1*4 + 7*3 = 25.

%F a(n) = Sum_{k=1..n} n^c(n), where c(n) is the characteristic function of nonprimes (A005171).

%t Table[n + (n - 1)*(n - PrimePi[n]), {n, 50}]

%Y Cf. A000720 (pi), A005171, A345888.

%K nonn

%O 1,2

%A _Wesley Ivan Hurt_, Jun 28 2021