A295793 a(n) is the least k such that A295520(k) = n.

2, 4, 0, 8, 25, 24, 35, 34, 201, 200, 203, 202, 297, 296, 299, 298, 1335, 1334, 1333, 1332, 1331, 1330, 1329, 1328, 3295, 3294, 3293, 3292, 3291, 3290, 3289, 3288, 11749, 11748, 11761, 11760, 11745, 11744, 11765, 11764, 11757, 11756, 19623, 19622, 11753, 11752, 19619, 19618, 25475, 25474, 25473, 25472

Offset: 0

Author

Robert Israel, Nov 27 2017

Keywords

• nonn
• base
• look

Examples

			a(3)=8 because A295520(8)=3 and this is the first appearance of 3 in A295520.
		

Links

• Robert Israel, Table of n, a(n) for n = 0..175

Crossrefs

Cf. A295520.

Programs

Maple

N:= 100: # to get a(0)..a(N)
A295520:= proc(n) local k;
  for k from 0 do if isprime(Bits:-Xor(k,n)) then return k fi od
end proc:
V:= Array(0..N,-1):
count:= 0:
for n from 0 while count < N+1 do
r:= A295520(n);
if r <= N and V[r]=-1 then
   count:= count+1; V[r]:= n
fi
od:
convert(V,list); # Robert Israel, Nov 27 2017

Mathematica

With[{s = Array[Block[{k = 0}, While[! PrimeQ@ BitXor[k, #], k++]; k] &, 10^6]}, FirstPosition[s, #][[1]] /. 1 -> 0 & /@ Take[#, LengthWhile[Differences@ #, # == 1 &]] &@ Union@ s] (* Michael De Vlieger, Nov 27 2017 *)

Python

from itertools import count
from sympy import isprime
def A295793(n): return next(k for k in count(0) if next((m for m in range(n+1) if isprime(k^m)),None)==n) # Chai Wah Wu, Aug 23 2023