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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.
7
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
0,5
COMMENTS
Digit reversal variation of tribonacci numbers A000073.
Inspired by Iccanobif numbers: A001129, A014258-A014260.
LINKS
FORMULA
A004086(a(n)) = A102125(n).
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 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
STATUS
approved