A369042 LCM-transform of the inverse of binary Gray code (A006068).

1, 3, 2, 7, 1, 2, 5, 1, 1, 1, 13, 2, 3, 11, 1, 31, 1, 1, 29, 1, 5, 3, 1, 2, 17, 19, 1, 23, 1, 1, 1, 1, 1, 1, 61, 1, 1, 59, 1, 1, 7, 1, 1, 1, 1, 1, 53, 2, 1, 1, 1, 1, 1, 1, 37, 47, 1, 1, 1, 1, 41, 43, 1, 127, 1, 1, 5, 1, 11, 1, 1, 1, 113, 1, 1, 1, 1, 1, 1, 1, 97, 1, 1, 103, 1, 1, 101, 1, 1, 1, 109, 1, 1, 107, 1, 2, 1

Offset: 1

Author

Antti Karttunen, Jan 12 2024

Keywords

• nonn

Comments

Inverse of Binary Gray code, A006068, is a permutation related to the binary expansion of n that keeps all the numbers of range [2^k, 2^(1+k)[ in the same range, i.e., for all n >= 1, A000523(A006068(n)) = A000523(n), from which it immediately follows that A006068 has the property S mentioned in the comments of A368900, and therefore this sequence is equal to A014963(A006068(n)), for n >= 1.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..16384
• Index entries for sequences related to binary expansion of n

Crossrefs

Cf. A006068, A014963, A368900, A369041, A369043, A369044.

Programs

PARI

up_to = 65537; \\ Checked up to 2^17;
LCMtransform(v) = { my(len = length(v), b = vector(len), g = vector(len)); b[1] = g[1] = 1; for(n=2,len, g[n] = lcm(g[n-1],v[n]); b[n] = g[n]/g[n-1]); (b); };
A006068(n)= { my(s=1, ns); while(1, ns = n >> s; if(0==ns, break()); n = bitxor(n, ns); s <<= 1; ); return (n); } \\ From A006068
v369042 = LCMtransform(vector(up_to,i,A006068(i)));
A369042(n) = v369042[n];
A014963(n) = { ispower(n, , &n); if(isprime(n), n, 1); };

Formula

a(n) = lcm {1..A006068(n)} / lcm {1..A006068(n-1)}.

a(n) = A014963(A006068(n)). [See comments.]