A102124 Iccanobirt numbers (14 of 15): a(n) = R(R(a(n-1)) + R(a(n-2)) + a(n-3)), where R is the digit reversal function A004086.

0, 0, 1, 1, 2, 4, 7, 31, 42, 44, 99, 581, 823, 216, 1251, 6592, 3964, 98, 47311, 72451, 99862, 73698, 789881, 684873, 171146, 8359081, 2855313, 6626115, 92901661, 80528542, 25591874, 127303561, 518156392, 14745484, 711014964, 521206301

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

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

Crossrefs

Cf. A102111-A102125.

Programs

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)) + 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]]+a[n-3]];Table[a[n], {n, 0, 40}]

Formula

a(n) = A004086(A102116(n)).