login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A001129
Iccanobif numbers: reverse digits of two previous terms and add.
36
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
KEYWORD
nonn,base,easy,nice
STATUS
approved