login
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.
19
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
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
KEYWORD
nonn,base,easy
AUTHOR
STATUS
approved