A001129 Iccanobif numbers: reverse digits of two previous terms and add.

0, 1, 1, 2, 3, 5, 8, 13, 39, 124, 514, 836, 1053, 4139, 12815, 61135, 104937, 792517, 1454698, 9679838, 17354310, 9735140, 1760750, 986050, 621360, 113815, 581437, 1252496, 7676706, 13019288, 94367798, 178067380, 173537220, 106496242, 265429972, 522619163

Offset

0,4

Links

Alois P. Heinz, Table of n, a(n) for n = 0..1000 (terms 0..300 from T. D. Noe)

Maple

R:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||n):
a:= proc(n) option remember; `if`(n<2, n,
       R(a(n-1)) +R(a(n-2)))
    end:
seq(a(n), n=0..50);  # Alois P. Heinz, Jun 18 2014

Mathematica

Clear[ BIF ]; BIF[ 0 ]=0; BIF[ 1 ]=1; BIF[ n_Integer ] := BIF[ n ]=Plus@@Map[ Plus@@(#*Array[ 10^#&, Length[ # ], 0 ])&, Map[ IntegerDigits, {BIF[ n-1 ], BIF[ n-2 ]} ] ]; Array[ BIF, 40, 0 ]
nxt[{a_, b_}]:={b, Total[FromDigits/@Reverse/@IntegerDigits[ {a, b}]]}; Transpose[NestList[nxt, {0, 1}, 40]][[1]] (* Harvey P. Dale, Jun 22 2011 *)
nxt[{a_, b_}]:={b, Total[IntegerReverse[{a, b}]]}; NestList[nxt, {0, 1}, 40][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 07 2019 *)

Prog

(PARI) A001129(n, a=0, b=1)={ n || return; while( n-->0, b=A004086(a)+A004086(a=b)); b }
(Haskell)
a001129 n = a001129_list !! n
a001129_list = 0 : 1 : zipWith (+) iccanobifs (tail iccanobifs)
where iccanobifs = map a004086 a001129_list
-- Reinhard Zumkeller, Jan 01 2012
(Python)
A001129_list, r1, r2 = [0, 1], 1, 0
for _ in range(10**2):
    l, r2 = r1+r2, r1
    r1 = int(str(l)[::-1])
    A001129_list.append(l) # Chai Wah Wu, Jan 03 2015
(Magma) a:=[0, 1]; [n le 2 select a[n] else Seqint(Reverse(Intseq(Self(n-1)))) + Seqint(Reverse(Intseq(Self(n-2)))):n in [1..35]]; // Marius A. Burtea, Oct 23 2019

Crossrefs

Cf. A001129, A014258, A014259, A014260.

Sequence in context: A042163 A273045 A014259 * A281599 A041957 A329192

Adjacent sequences: A001126 A001127 A001128 * A001130 A001131 A001132

Keyword

nonn,base,easy,nice

Author

N. J. A. Sloane

Status

approved