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A102111
Iccanobirt numbers (1 of 15): a(n) = a(n-1) + a(n-2) + R(a(n-3)), where R is the digit reversal function A004086.
19
0, 0, 1, 1, 2, 4, 7, 13, 24, 44, 99, 185, 328, 612, 1521, 2956, 4693, 8900, 20185, 33049, 53332, 144483, 291848, 459666, 1135955, 2443813, 4246722, 12285846, 19716010, 34278280, 118852511, 154192582, 281332336, 550783729, 1117407516, 2301424427
OFFSET
0,5
COMMENTS
Digit reversal variation of tribonacci numbers A000073.
Inspired by Iccanobif numbers: A001129, A014258-A014260.
FORMULA
A004086(a(n)) = A102119(n).
MAPLE
read("transforms") ;
A102111 := proc(n)
option remember;
if n <= 2 then
return op(n+1, [0, 0, 1]) ;
else
return procname(n-1)+procname(n-2)+digrev(procname(n-3)) ;
end if;
end proc:
seq(A102111(n), n=0..20) ; # R. J. Mathar, Nov 17 2012
MATHEMATICA
R[n_]:=FromDigits[Reverse[IntegerDigits[n]]]; Clear[a]; a[0]=0; a[1]=0; a[2]=1; a [n_]:=a[n]=a[n-1]+a[n-2]+R[a[n-3]]; Table[a[n], {n, 0, 40}]
nxt[{a_, b_, c_}]:={b, c, IntegerReverse[a]+b+c}; NestList[nxt, {0, 0, 1}, 40][[;; , 1]] (* Harvey P. Dale, Jul 18 2023 *)
PROG
(Python)
def R(n):
n_str = str(n)
reversedn_str = n_str[::-1]
reversedn = int(reversedn_str)
return reversedn
def A(n):
if n == 0:
return 0
elif n == 1:
return 0
elif n == 2:
return 1
elif n >= 3:
return A(n-1)+A(n-2)+R(A(n-3))
for i in range(0, 20):
print(A(i)) # Dylan Delgado, Oct 23 2019
(Magma) a:=[0, 0, 1]; [n le 3 select a[n] else Self(n-1) + Self(n-2) + Seqint(Reverse(Intseq(Self(n-3)))):n in [1..36]]; // Marius A. Burtea, Oct 23 2019
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
STATUS
approved