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 1-3 of 3 results.

A119475 Inverse of permutation sequence A119474.

Original entry on oeis.org

1, 2, 3, 5, 4, 9, 6, 17, 7, 10, 33, 8, 11, 18, 13, 12, 65, 19, 34, 14, 21, 20, 15, 129, 35, 25, 16, 22, 66, 37, 23, 36, 257, 26, 24, 67, 41, 38, 27, 130, 69, 29, 28, 39, 49, 68, 42, 40, 30, 513, 131, 73, 31, 43, 70, 258, 45, 32, 44, 50, 133, 71, 81, 132, 46, 51, 74, 72, 47, 1025
Offset: 1

Views

Author

Leroy Quet, May 22 2006

Keywords

Comments

Sequence is a permutation of the positive integers.

Crossrefs

Cf. A119474.

Programs

  • PARI
    See Links section.

Extensions

More terms from Joshua Zucker, Jul 04 2006

A101267 a(1) = 1; a(n) = a(2^ceiling(log_2(n)) + 1 - n)th smallest positive integer not yet in the sequence.

Original entry on oeis.org

1, 2, 4, 3, 7, 9, 6, 5, 13, 15, 19, 17, 11, 14, 10, 8, 24, 27, 32, 29, 37, 40, 35, 33, 21, 23, 30, 26, 18, 22, 16, 12, 44, 49, 56, 52, 62, 67, 59, 57, 73, 76, 82, 79, 69, 74, 66, 63, 39, 43, 50, 46, 58, 64, 54, 51, 34, 38, 47, 42, 28, 36, 25, 20, 84, 90, 102, 94, 110, 116, 106
Offset: 1

Views

Author

Leroy Quet, Dec 18 2004

Keywords

Comments

Sequence is a permutation of the positive integers. 2^ceiling(log_2(n)) + 1 - n is sequence A080079 with a change of offset.

Examples

			Since 2^ceiling(log_2(n)) +1 -n = 3 at n = 6, a(6) = the a(3)th (the 4th) smallest positive integer not among the first 5 terms of the sequence. The positive integers not among the first 5 terms are 5,6,8,9,10,... The 4th of these is 9, which is a(6).
		

Crossrefs

Programs

  • Mathematica
    a[1] = 1; a[n_] := a[n] = Complement[ Range[100], Table[ a[i], {i, n - 1}]] [[ a[2^Ceiling[ Log[2, n]] + 1 - n]]]; Table[ a[n], {n, 71}] (* Robert G. Wilson v, Jan 13 2005 *)

Extensions

More terms from Robert G. Wilson v, Jan 13 2005

A119804 a(0) = 0. For m >= 0 and 0 <= k <= 2^m -1, a(2^m +k) = number of earlier terms of the sequence which equal k.

Original entry on oeis.org

0, 1, 1, 2, 1, 3, 1, 1, 1, 6, 1, 1, 0, 0, 1, 0, 4, 9, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 13, 14, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 36, 21, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0
Offset: 0

Views

Author

Leroy Quet, May 24 2006

Keywords

Examples

			8 = 2^3 + 0; so for a(8) we want the number of terms among terms a(1), a(2),... a(7) which equal 0. So a(8) = 1.
		

Crossrefs

Programs

  • PARI
    A119804(mmax)= { local(a,ncopr); a=[0]; for(m=0,mmax, for(k=0,2^m-1, ncopr=0; for(i=1,2^m+k, if( a[i]==k, ncopr++; ); ); a=concat(a,ncopr); ); ); return(a); } { print(A119804(6)); } \\ R. J. Mathar, May 30 2006

Extensions

More terms from R. J. Mathar, May 30 2006
Showing 1-3 of 3 results.