A102117 Iccanobirt numbers (7 of 15): a(n) = R(a(n-1)) + R(a(n-2)) + R(a(n-3)), where R is the digit reversal function A004086.

0, 0, 1, 1, 2, 4, 7, 13, 42, 62, 81, 68, 130, 135, 648, 1408, 9418, 17036, 79261, 87517, 150946, 736926, 1350266, 7899219, 16380155, 70858879, 162124155, 704415429, 1573821475, 7217219419, 15814925285, 73143352729, 160127403115

Offset: 0

Author

Jonathan Vos Post and Ray Chandler, Dec 30 2004

Keywords

• nonn
• base
• easy

Comments

Digit reversal variation of tribonacci numbers A000073.

Inspired by Iccanobif numbers: A001129, A014258-A014260.

Links

• Robert Israel, Table of n, a(n) for n = 0..2664

Crossrefs

Cf. A102111-A102125.

Programs

Maple

rev:= proc(n) local i, L;
L:= convert(n,base, 10);
add(L[-i]*10^(i-1),i=1..nops(L))
end proc:
A[0]:= 0: A[1]:= 0: A[2]:= 1:
RA[0]:=0: RA[1]:= 0: RA[2]:= 1:
for n from 3 to 100 do
  A[n]:= RA[n-1]+RA[n-2]+RA[n-3];
  RA[n]:= rev(A[n]);
od:
seq(A[n],n=0..100); # Robert Israel, Aug 04 2016

Mathematica

R[n_]:=FromDigits[Reverse[IntegerDigits[n]]];Clear[a];a[0]=0;a[1]=0;a[2]=1;a [n_]:=a[n]=R[a[n-1]]+R[a[n-2]]+R[a[n-3]];Table[a[n], {n, 0, 40}]
nxt[{a_,b_,c_}]:={b,c,Total[IntegerReverse/@{a,b,c}]}; Transpose[ NestList[ nxt,{0,0,1},40]][[1]] (* The program uses the IntegerReverse function from Mathematica version 10 *) (* Harvey P. Dale, Nov 28 2015 *)

Formula

A004086(a(n)) = A102125(n).