This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
a[n_] := a[n] = a[n - 1] + a[n - 2] + IntegerReverse[a[n - 3]]; a[0] = 0; a[1] = 0; a[2] = 1; Select[Range[0, 5000], PrimeQ[a[#]] &] (* Robert Price, Apr 10 2020 *)
a[n_] := a[n] = a[n - 1] + IntegerReverse[a[n - 2]] + a[n - 3]; a[0] = 0; a[1] = 0; a[2] = 1; Select[Range[0, 5000], PrimeQ[a[#]] &] (* Robert Price, Apr 10 2020 *)
a[n_] := a[n] = IntegerReverse[IntegerReverse[a[n - 1]] + IntegerReverse[a[n - 2]] + a[n - 3]]; a[0] = 0; a[1] = 0; a[2] = 1; Select[Range[0, 5000], PrimeQ[a[#]] &] (* Robert Price, Apr 10 2020 *)
nxt[{a_, b_, c_}] := {b, c, c + IntegerReverse[b] + IntegerReverse[a]}; Flatten[Position[NestList[nxt,{0,0,1},3500][[All,1]],?PrimeQ]]-1 (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale, Sep 10 2016 *)
nxt[{a_,b_,c_}]:={b,c,FromDigits[Reverse[IntegerDigits[c]]]+b+a}; Flatten[ Position[Transpose[NestList[nxt,{0,0,1},2500]][[1]],?PrimeQ]-1] (* _Harvey P. Dale, May 30 2012 *)
a[n_] := a[n] = IntegerReverse[a[n - 1]] + a[n - 2] + IntegerReverse[a[n - 3]]; a[0] = 0; a[1] = 0; a[2] = 1; Select[Range[0, 5000], PrimeQ[a[#]] &] (* Robert Price, Apr 10 2020 *) nxt[{a_,b_,c_}]:={b,c,Total[IntegerReverse[{a,c}]]+b};Flatten[Position[NestList[nxt,{0,0,1},2600][[;;,1]],?PrimeQ]]-1 (* The program generates the first 10 terms of the sequence. *) (* _Harvey P. Dale, Oct 23 2024 *)
a[n_] := a[n] = IntegerReverse[a[n - 1]] + IntegerReverse[a[n - 2]] + a[n - 3]; a[0] = 0; a[1] = 0; a[2] = 1; Select[Range[0, 5000], PrimeQ[a[#]] &] (* Robert Price, Apr 10 2020 *)
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: count:= 0: for n from 3 to 10000 do A[n]:= RA[n-1]+RA[n-2]+RA[n-3]; RA[n]:= rev(A[n]); if isprime(A[n]) then count:= count+1; a[count]:= n fi od: seq(a[i],i=1..count); # Robert Israel, Aug 04 2016
Flatten[Position[Transpose[NestList[nxt,{0,0,1},1700]][[1]],?PrimeQ]]-1 (* _Harvey P. Dale, Nov 28 2015 *)
a[n_] := a[n] = IntegerReverse[(a[n - 1] + a[n - 2] + a[n - 3])]; a[0] = 0; a[1] = 0; a[2] = 1; Select[Range[0, 5000], PrimeQ[a[#]] &] (* Robert Price, Apr 10 2020 *)
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