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 1-7 of 7 results.

A272760 a(n) = A065880(n)/n.

Original entry on oeis.org

1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 5, 2, 0, 3, 4, 1, 2, 2, 0, 2, 6, 5, 5, 2, 0, 0, 4, 3, 4, 4, 5, 1, 2, 2, 0, 2, 6, 0, 4, 2, 6, 6, 4, 5, 4, 5, 0, 2, 0, 0, 4, 0, 6, 4, 0, 3, 5, 4, 5, 4, 6, 5, 6, 1, 2, 2, 0, 2, 6, 0, 5, 2, 6, 6, 4, 0, 6, 4, 6, 2, 6, 6, 6, 6, 5, 4, 3
Offset: 1

Views

Author

Peter Kagey, May 05 2016

Keywords

Comments

This sequence is bounded above by A272756.
a(n) is the greatest value i such that A000120(n * i) = i or 0 if no such value exists.

Crossrefs

Programs

  • Mathematica
    Table[SelectFirst[Reverse@ Range@ #, First@ DigitCount[#, 2] == #/n &] &[n SelectFirst[Range[2^12], # > IntegerLength[n #, 2] &]]/n, {n, 120}] /. k_ /; MissingQ@ k -> 0 (* Michael De Vlieger, May 05 2016, Version 10.2 *)

A272761 List of indices i such that A065879(i) != A065880(i).

Original entry on oeis.org

23, 27, 37, 41, 46, 53, 54, 57, 69, 71, 74, 77, 79, 81, 82, 83, 85, 89, 91, 92, 101, 105, 106, 107, 108, 113, 114, 121, 125, 133, 135, 138, 139, 141, 142, 143, 147, 148, 153, 154, 158, 161, 162, 163, 164, 166, 167, 169, 170, 173, 177, 178, 181, 182, 184, 197
Offset: 1

Views

Author

Peter Kagey, May 06 2016

Keywords

Comments

Equivalently a list of indices i such that A272759(i) != A272760(i).
Also, a list of indices i such that A065413(i) > 1.

Crossrefs

A065878 Numbers which are not an integer multiple of their number of binary 1's.

Original entry on oeis.org

3, 5, 7, 9, 11, 13, 14, 15, 17, 19, 22, 23, 25, 26, 27, 28, 29, 30, 31, 33, 35, 37, 38, 39, 41, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 54, 56, 57, 58, 59, 61, 62, 63, 65, 67, 70, 71, 73, 74, 75, 76, 77, 78, 79, 82, 83, 85, 86, 87, 88, 89, 90, 91, 93, 94, 95, 97, 98, 99, 100
Offset: 1

Views

Author

Henry Bottomley, Nov 26 2001

Keywords

Examples

			5 is in the sequence since 5 = 101_2 and 5 is not a multiple of 1 + 0 + 1 = 2.
		

Crossrefs

Complement of A049445.
The base-10 equivalent is A065877.

Programs

  • Mathematica
    Select[Range[100],!IntegerQ[#/Total[IntegerDigits[#,2]]]&]  (* Harvey P. Dale, Apr 20 2011 *)
  • PARI
    isok(k) = k % hammingweight(k); \\ Amiram Eldar, Aug 04 2025

A065879 a(n) is the smallest positive number that is n times the number of 1's in its binary expansion, or 0 if no such number exists.

Original entry on oeis.org

1, 2, 6, 4, 10, 12, 21, 8, 18, 20, 55, 24, 0, 42, 60, 16, 34, 36, 0, 40, 126, 110, 69, 48, 0, 0, 81, 84, 116, 120, 155, 32, 66, 68, 0, 72, 185, 0, 156, 80, 205, 252, 172, 220, 180, 138, 0, 96, 0, 0, 204, 0, 212, 162, 0, 168, 228, 232, 295, 240, 366, 310, 378, 64, 130
Offset: 1

Views

Author

Henry Bottomley, Nov 26 2001

Keywords

Comments

a(n) is bounded above by n*A272756(n), so a program only has to check values up to that point to see if a(n) is zero. - Peter Kagey, May 05 2016

Examples

			a(23) is 69 since 69 is written in binary as 1000101, 69/(1+0+0+0+1+0+1)=23 and there is no smaller possibility (neither 23 nor 46 are divisible by their number of binary 1's).
		

Crossrefs

A003634 is the base-10 equivalent.

Programs

  • Mathematica
    Table[SelectFirst[Range[2^12], # == n First@ DigitCount[#, 2] &] /. k_ /; MissingQ@ k -> 0, {n, 80}] (* Michael De Vlieger, May 05 2016, Version 10.2 *)

A277249 Largest number that is n times sum of its digits when written in base 3.

Original entry on oeis.org

0, 2, 8, 6, 16, 25, 24, 35, 32, 18, 80, 77, 48, 78, 56, 75, 64, 0, 72, 152, 160, 105, 132, 115, 96, 150, 156, 54, 224, 232, 240, 186, 0, 231, 204, 210, 144, 296, 228, 234, 320, 287, 168, 172, 0, 225, 368, 376, 192, 392, 400, 0, 312, 371, 216, 440, 448, 456
Offset: 0

Views

Author

Daniel Mondot, Oct 06 2016

Keywords

Crossrefs

Formula

a(n) = 0 for n in A058899. - Michel Marcus, Oct 09 2016

A277250 Largest number that is n times sum of its digits when written in base 4.

Original entry on oeis.org

0, 3, 6, 9, 12, 30, 18, 63, 24, 54, 60, 33, 36, 91, 126, 90, 48, 102, 108, 190, 120, 189, 154, 207, 72, 250, 234, 243, 252, 0, 180, 248, 96, 198, 204, 315, 216, 148, 228, 351, 240, 0, 378, 430, 132, 270, 506, 423, 144, 490, 300, 459, 364, 477, 486, 440, 504
Offset: 0

Views

Author

Daniel Mondot, Oct 06 2016

Keywords

Crossrefs

Formula

a(n) = 0 for n in A058900. - Michel Marcus, Oct 09 2016

A277291 Largest number that is n times sum of its digits when written in base 5.

Original entry on oeis.org

0, 4, 8, 24, 16, 20, 48, 42, 64, 99, 40, 88, 96, 117, 112, 120, 0, 102, 144, 76, 80, 189, 0, 184, 192, 100, 208, 324, 0, 348, 240, 372, 128, 363, 272, 210, 288, 444, 304, 624, 320, 574, 336, 258, 352, 495, 0, 564, 384, 588, 200, 612, 416, 583, 432, 440, 0, 570
Offset: 0

Views

Author

Daniel Mondot, Oct 09 2016

Keywords

Crossrefs

Formula

a(n) = 0 for n in A058901. - Michel Marcus, Oct 09 2016
Showing 1-7 of 7 results.