A102125 - OEIS

%I #13 Dec 19 2015 00:24:31

%S 0,0,1,1,2,4,7,31,42,44,18,941,472,405,729,5071,6313,8675,90601,31591,

%T 9853,11733,31865,31149,736481,365533,313416,3154311,9834802,5123383,

%U 7112507,12796921,35055832,19867834,56610708,906334841,561210372

%N Iccanobirt numbers (15 of 15): a(n) = R(R(a(n-1)) + R(a(n-2)) + R(a(n-3))), where R is the digit reversal function A004086.

%C Digit reversal variation of tribonacci numbers A000073.

%C Inspired by Iccanobif numbers: A001129, A014258-A014260.

%H Alois P. Heinz, <a href="/A102125/b102125.txt">Table of n, a(n) for n = 0..1000</a>

%F a(n) = A004086(A102117(n)).

%p R:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||n):

%p a:= proc(n) option remember; `if`(n<3, binomial(n,2),

%p       R(R(a(n-1)) + R(a(n-2)) + R(a(n-3))))

%p     end:

%p seq(a(n), n=0..50);  # _Alois P. Heinz_, Jun 18 2014

%t R[n_]:=FromDigits[Reverse[IntegerDigits[n]]];Clear[a];a[0]=0;a[1]=0;a[2]=1;a [n_]:=a[n]=R[R[a[n-1]]+R[a[n-2]]+R[a[n-3]]];Table[a[n], {n, 0, 40}]

%t rev[n_]:=FromDigits[Reverse[IntegerDigits[n]]]; nxt[{a_, b_, c_}] := {b, c, rev[rev[a] + rev[b] + rev[c]]}; Transpose[NestList[nxt,{0,0,1},40]][[1]] (* _Harvey P. Dale_, Mar 20 2015 *)

%Y Cf. A102111-A102124.

%K nonn,base,easy

%O 0,5

%A _Jonathan Vos Post_ and _Ray Chandler_, Dec 30 2004