A102111 - OEIS

%I #25 Jul 18 2023 16:12:29

%S 0,0,1,1,2,4,7,13,24,44,99,185,328,612,1521,2956,4693,8900,20185,

%T 33049,53332,144483,291848,459666,1135955,2443813,4246722,12285846,

%U 19716010,34278280,118852511,154192582,281332336,550783729,1117407516,2301424427

%N 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.

%C Digit reversal variation of tribonacci numbers A000073.

%C Inspired by Iccanobif numbers: A001129, A014258-A014260.

%F A004086(a(n)) = A102119(n).

%p read("transforms") ;

%p A102111 := proc(n)

%p     option remember;

%p     if n <= 2 then

%p         return op(n+1,[0,0,1]) ;

%p     else

%p         return procname(n-1)+procname(n-2)+digrev(procname(n-3)) ;

%p     end if;

%p end proc:

%p seq(A102111(n),n=0..20) ; # _R. J. Mathar_, Nov 17 2012

%t 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}]

%t nxt[{a_,b_,c_}]:={b,c,IntegerReverse[a]+b+c}; NestList[nxt,{0,0,1},40][[;;,1]] (* _Harvey P. Dale_, Jul 18 2023 *)

%o (Python)

%o def R(n):

%o   n_str = str(n)

%o   reversedn_str = n_str[::-1]

%o   reversedn = int(reversedn_str)

%o   return reversedn

%o def A(n):

%o   if n == 0:

%o     return 0

%o   elif n == 1:

%o     return 0

%o   elif n == 2:

%o     return 1

%o   elif n >= 3:

%o     return A(n-1)+A(n-2)+R(A(n-3))

%o for i in range(0,20):

%o   print(A(i)) # _Dylan Delgado_, Oct 23 2019

%o (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

%Y Cf. A102112-A102125, A102131, A102171.

%K nonn,base,easy

%O 0,5

%A _Jonathan Vos Post_ and _Ray Chandler_, Dec 30 2004