G.f.: Sum_{k >= 1} (phi(k)/k)*log(1-f(x^k)), where f(x) = (1 - sqrt(1 - 4*x)) / (2*x) - 1 is the g.f. for the Catalan numbers (A000108) C_1, C_2, C_3, ...

A060404

G.f.: Sum_{k >= 1} (phi(k)/k)*log(1-f(x^k)), where f(x) = (1 - sqrt(1 - 4*x)) / (2*x) - 1 is the g.f. for the Catalan numbers (A000108) C_1, C_2, C_3, ...

Terms

    a(0) =0a(1) =1a(2) =3a(3) =8a(4) =25a(5) =78a(6) =270a(7) =926a(8) =3305a(9) =11868a(10) =43232a(11) =158586a(12) =586530a(13) =2181088a(14) =8154710a(15) =30620868a(16) =115435625a(17) =436654794a(18) =1656793374a(19) =6303490610a(20) =24041649128a(21) =91899730068a(22) =352002058402

External references