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.

A100805 Inverse permutation to sequence A101319 (assuming A101319 is a permutation).

Original entry on oeis.org

1, 2, 3, 8, 9, 4, 5, 7, 29, 67, 69, 6, 41, 10, 18, 28, 11, 13, 65, 27, 14, 562, 23, 64, 595, 45, 30, 12, 203, 19, 20, 68, 57, 211, 15, 56, 42, 35, 890, 17, 46, 52, 24, 55, 36, 60, 2363, 202, 216, 16, 21, 51, 8159, 31, 32, 26, 2029, 70, 53, 193, 301, 182, 12720, 66, 1004, 25
Offset: 1

Views

Author

Leroy Quet, Jan 04 2005

Keywords

Comments

a(53), if it exists, is greater than 5000. - Franklin T. Adams-Watters, May 12 2006

Crossrefs

Cf. A101319.

Extensions

More terms from Franklin T. Adams-Watters, May 12 2006
a(53) onwards from David Wasserman, Mar 04 2008

A318578 Let k be the greatest odd divisor of n and let S be the sequence of positive integers not in the sequence so far in increasing order. Then a(n) = S(k).

Original entry on oeis.org

1, 2, 5, 3, 9, 7, 13, 4, 17, 12, 21, 10, 25, 18, 29, 6, 33, 23, 37, 16, 41, 28, 45, 14, 49, 34, 53, 24, 57, 39, 61, 8, 65, 44, 69, 31, 73, 50, 77, 22, 81, 55, 85, 38, 89, 60, 93, 19, 97, 66, 101, 46, 105, 71, 109, 32, 113, 76, 117, 52, 121, 82, 125, 11, 129, 87, 133
Offset: 1

Views

Author

Ivan Neretin, Aug 29 2018

Keywords

Comments

In other words, a(n) = A000265(n)-th positive integer unused so far.
A permutation of the positive integers.
a(n) = 2n - 1 for odd n, a(n) < 2n - 1 otherwise.

Examples

			For n=6, the highest odd divisor of n is k = 3. The sequence up to that point is 1, 2, 5, 3, 9. The numbers which are not yet in the sequence (in increasing order) are S = 4, 6, 7, 8, 10, ... and the 3rd of these is 7, which is therefore a(6).
		

Crossrefs

Programs

  • Mathematica
    Fold[Append[#1, Complement[Range[Max[#1] + (r = #2/2^IntegerExponent[#2, 2])], #1][[r]]] &, {1}, Range[2, 67]]
Showing 1-2 of 2 results.