a(n) = sum_{k=1 to n} A139019(k).A139020a(n) = sum_{k=1 to n} A139019(k).Terms a(0) =1a(1) =3a(2) =8a(3) =19a(4) =32a(5) =49a(6) =128a(7) =211a(8) =33554432a(9) =67108933External referencesoeis: A139020