A035524 Reverse and add (in base 4).

1, 2, 4, 5, 10, 20, 25, 50, 85, 170, 340, 425, 850, 1385, 3070, 6140, 10225, 15335, 29410, 65135, 129070, 317675, 1280860, 2163725, 3999775, 7999550, 20321515, 81946460, 138412045, 255852575, 511705150, 1300234475, 5242880860

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy
• nice
• base

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..1000
• Index entries for sequences related to Reverse and Add!

Crossrefs

Cf. A035522.

Cf. A030103.

Programs

Haskell

a035524 n = a035524_list !! n
a035524_list = iterate a055948 1
-- Reinhard Zumkeller, Oct 10 2011

Mathematica

nxt4[n_]:=Module[{idn4=IntegerDigits[n,4]},FromDigits[idn4+ Reverse[idn4], 4]]; NestList[nxt4,1,40] (* Harvey P. Dale, May 02 2011 *)

Python

def reversedigits(n, b=10): # reverse digits of n in base b
    x, y = n, 0
    while x >= b:
        x, r = divmod(x, b)
        y = b*y + r
    return b*y + x
A035524_list, l = [1], 1
for _ in range(50):
    l += reversedigits(l,4)
    A035524_list.append(l)

Formula

a(n+1) = A055948(a(n)), a(0) = 1. [Reinhard Zumkeller, Oct 10 2011]

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Sep 22 2000