cp's OEIS Frontend

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.

Showing 1-2 of 2 results.

A357993 a(n) is the unique k such that A357961(k) = 2^n.

Original entry on oeis.org

1, 2, 9, 8, 17, 34, 64, 129, 252, 515, 1026, 2044, 4091, 8184, 16375, 32758, 65525, 131060, 262131, 524279, 1048566, 2097167, 4194322, 8388590, 16777203, 33554450, 67108877, 134217712, 268435473, 536870929, 1073741807, 2147483622, 4294967278, 8589934615
Offset: 0

Views

Author

Rémy Sigrist, Oct 23 2022

Keywords

Comments

Conjecture: if we write a(m) = 2^m + d then d < 2*m for m > 2. The reason for this conjecture: the Hamming weight of a number is smaller than its binary logarithm. If we assume in A357961 a random distribution of Hamming weights with values < log_2(k) for A357961(k), then we may expect for each dyadic interval an increase in displacement by the half of the intervals exponent. If we assume instead of randomness a stronger repeating of any Hamming weight, we would even reduce the gained displacement by this. - Thomas Scheuerle, Oct 24 2022

Examples

			A357961(1026) = 1024 = 2^10, so a(10) = 1026.
		

Crossrefs

Cf. A357961.

Programs

  • PARI
    See Links section.

Formula

Empirically: a(n) ~ 2^n.

A358057 Inverse permutation to A357961.

Original entry on oeis.org

1, 2, 3, 9, 4, 5, 6, 8, 7, 10, 18, 11, 12, 15, 13, 17, 14, 16, 35, 24, 19, 20, 21, 23, 22, 25, 30, 26, 27, 32, 28, 34, 29, 31, 65, 33, 40, 36, 37, 39, 38, 48, 41, 46, 42, 43, 44, 47, 45, 61, 49, 55, 50, 51, 52, 54, 53, 56, 130, 57, 58, 62, 59, 64, 60, 67, 63
Offset: 1

Views

Author

Rémy Sigrist, Oct 28 2022

Keywords

Examples

			A357961(42) = 45, so a(45) = 42.
		

Crossrefs

Cf. A357961.

Programs

  • PARI
    See Links section.
Showing 1-2 of 2 results.