A129098 a(n) = A129095(2^n + 2^(n-1) - 1) for n>=1.

1, 5, 23, 135, 1119, 14319, 300015, 10636463, 652217135, 70382845743, 13551477257519, 4706105734658351, 2973879284783561007, 3444999327807280048431, 7362415635261959807011119, 29188908702092573515760044335

Offset: 1

Author

Paul D. Hanna, Apr 11 2007

Keywords

• easy
• nonn

Comments

b(n)=A129095(n) obeys the recurrence: b(n) = b(n/2) (n even), b(n) = 2*b(n-1) + b(n-2) (n odd >1), with b(1) = 1.

Crossrefs

Cf. A129095, A129096, A129097, A129099.

Programs

Mathematica

Block[{e = 18, s}, s = Nest[Append[#1, If[EvenQ[#2], #1[[#2/2]], 2 #1[[-1]] + #1[[-2]] ] ] & @@ {#, Length@ # + 1} &, {1}, 2^e]; Array[s[[2^# + 2^(# - 1) - 1]] &, e - 1]] (* Michael De Vlieger, Mar 10 2020 *)

PARI

Extensions

a(16) from Michael De Vlieger, Mar 10 2020.