a(n) = ( Sum C(p,i); i=1,...,floor(2p/3) ) / p^2, where p = prime(n).
A001007
a(n) = ( Sum C(p,i); i=1,...,floor(2p/3) ) / p^2, where p = prime(n).
Terms
- a(0) =1a(1) =2a(2) =15a(3) =42a(4) =421a(5) =1331a(6) =15119a(7) =618765a(8) =2155578a(9) =98032875a(10) =1290154807a(11) =4682196239a(12) =63117678751
External references
- oeis: A001007