A295079 a(n) = least k > n such that A002487(k) = A002487(n).

2, 4, 6, 8, 7, 12, 10, 16, 15, 14, 13, 24, 17, 20, 18, 32, 22, 30, 23, 28, 27, 26, 25, 48, 29, 31, 42, 40, 38, 36, 34, 64, 63, 44, 47, 60, 41, 46, 57, 56, 55, 54, 53, 52, 51, 50, 49, 96, 61, 58, 90, 62, 71, 84, 59, 80, 78, 65, 67, 72, 70, 68, 66, 128, 76, 126

Offset: 1

Author

Rémy Sigrist, Nov 13 2017

Keywords

• nonn

Comments

See A091926 for the least k such that A002487(k) = A002487(n).

For any n > 0, a(n) <= 2*n, with equality iff n belongs to A029744.

For any n > 0, there is a constant i >= 0 such that for any k >= 0, a^(i + k*A000010(A002487(n)))(n) = 2^k * a^i(n) (where a^m denotes the m-th iterate of the sequence a); this comes from the fact that a value v > 0 eventually appears A000010(v) times in each row of A002487.

Examples

			A002487(n) = 5 for n = 11, 13, 17, 22, 26, 31, 34, 44, 52, 62, ...
Hence a(11) = 13, a(13) = 17, a(17) = 22, a(22) = 26, etc.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..8192
• Index entries for sequences related to Stern's sequences

Crossrefs

Cf. A000010, A002487, A029744, A091926.

Programs

PARI

fusc(n)=local(a=1, b=0); while(n>0, if(bitand(n, 1), b+=a, a+=b);n>>=1); b \\ after Charles R Greathouse IV at A002487
a(n) = my (v=fusc(n)); for (k=n+1, oo, if (fusc(k)==v, return (k)))