A102125 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.

0, 0, 1, 1, 2, 4, 7, 31, 42, 44, 18, 941, 472, 405, 729, 5071, 6313, 8675, 90601, 31591, 9853, 11733, 31865, 31149, 736481, 365533, 313416, 3154311, 9834802, 5123383, 7112507, 12796921, 35055832, 19867834, 56610708, 906334841, 561210372

Offset

0,5

Comments

Digit reversal variation of tribonacci numbers A000073.

Inspired by Iccanobif numbers: A001129, A014258-A014260.

Links

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Formula

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

Maple

R:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||n):
a:= proc(n) option remember; `if`(n<3, binomial(n, 2),
      R(R(a(n-1)) + R(a(n-2)) + R(a(n-3))))
    end:
seq(a(n), n=0..50);  # Alois P. Heinz, Jun 18 2014

Mathematica

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}]
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 *)

Crossrefs

Cf. A102111-A102124.

Sequence in context: A280377 A102122 A102123 * A102124 A280713 A233868

Adjacent sequences: A102122 A102123 A102124 * A102126 A102127 A102128

Keyword

nonn,base,easy

Author

Jonathan Vos Post and Ray Chandler, Dec 30 2004

Status

approved