Sum of integers generated by n-1 substitutions, starting with 1, k -> k+1, k-1, .., 1.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =17a(5) =36a(6) =80a(7) =176a(8) =403a(9) =910a(10) =2128a(11) =4896a(12) =11628a(13) =27132a(14) =65208a(15) =153824a(16) =373175a(17) =888030a(18) =2170740a(19) =5202600a(20) =12797265a(21) =30853680a(22) =76292736a(23) =184863168a(24) =459162452a(25) =1117370696a(26) =2786017120a(27) =6804995008a(28) =17024247304a(29) =41717833740