a(0)=0, a(1)=1, a(n) = min{5 a(k) + (5^(n-k)-1)/4, k=0..(n-1)} for n>=2.

Terms

a(0) =0a(1) =1a(2) =6a(3) =11a(4) =36a(5) =61a(6) =86a(7) =211a(8) =336a(9) =461a(10) =586a(11) =1211a(12) =1836a(13) =2461a(14) =3086a(15) =3711a(16) =6836a(17) =9961a(18) =13086a(19) =16211a(20) =19336a(21) =22461a(22) =38086a(23) =53711a(24) =69336a(25) =84961a(26) =100586a(27) =116211a(28) =131836a(29) =209961