a(n) = A078343(n) + (-1)^n.

Terms

a(0) =0a(1) =1a(2) =4a(3) =7a(4) =20a(5) =45a(6) =112a(7) =267a(8) =648a(9) =1561a(10) =3772a(11) =9103a(12) =21980a(13) =53061a(14) =128104a(15) =309267a(16) =746640a(17) =1802545a(18) =4351732a(19) =10506007a(20) =25363748a(21) =61233501a(22) =147830752a(23) =356895003a(24) =861620760a(25) =2080136521a(26) =5021893804a(27) =12123924127a(28) =29269742060a(29) =70663408245