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 1-5 of 5 results.

A228082 Numbers that are of the form k + sum of binary digits of k for some nonnegative integer k.

Original entry on oeis.org

0, 2, 3, 5, 7, 8, 9, 10, 11, 12, 14, 16, 17, 19, 20, 22, 24, 25, 26, 27, 28, 29, 31, 33, 34, 35, 36, 38, 40, 41, 42, 43, 44, 45, 47, 49, 50, 52, 53, 55, 57, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 69, 70, 72, 73, 74, 75, 76, 77, 79, 81, 82, 84, 85, 87, 89, 90
Offset: 1

Views

Author

Antti Karttunen, Aug 09 2013

Keywords

Comments

Complement of A010061.
Obtained when A092391 is sorted and duplicates are removed.
The asymptotic density of this sequence is 1 - (1/8) * (Sum_{n>=1} 1/2^a(n))^2 = 1 - A242403 = 0.747339... - Amiram Eldar, Nov 28 2020

References

  • Steven R. Finch, Mathematical Constants, Cambridge, 2003, Section 2.24, pp. 179-180.
  • József Sándor and Borislav Crstici, Handbook of Number theory II, Kluwer Academic Publishers, 2004, Chapter 4, p. 384-386.
  • G. Troi and U. Zannier, Note on the density constant in the distribution of self-numbers, Bolletino U. M. I. (7) 9-A (1995), 143-148.

Crossrefs

Numbers that occur to the right of the leftmost column of A228083. Positions of nonzeros in A228085. A superset of A228088.
The even terms are the first row of A350601.

Programs

  • Haskell
    a228082 n = a228082_list !! (n-1)
    a228082_list = 0 : filter ((> 0) . a228085) [1..]
    -- Reinhard Zumkeller, Oct 13 2013
  • Mathematica
    Table[n + Total[IntegerDigits[n, 2]], {n, 0, 100}] // Union (* Jean-François Alcover, Sep 03 2013 *)

A230624 Numbers k with property that for every base b >= 2, there is a number m such that m+s(m) = k, where s(m) = sum of digits in the base-b expansion of m.

Original entry on oeis.org

0, 2, 10, 14, 22, 38, 62, 94, 158, 206, 318, 382, 478, 606, 766, 958, 1022, 1534, 1662, 1726, 1790, 1918, 1982, 2238, 2622, 2686, 3006, 3262, 3582, 3966, 4734, 5118, 5374, 5758, 5886, 6782, 8830, 9342, 9470, 9598, 10878, 12926, 13182, 13438, 14718, 18686, 22526
Offset: 1

Views

Author

N. J. A. Sloane, Oct 27 2013

Keywords

Comments

If k is a positive term then k is even (or else k has no generator in base k+1) but not a multiple of 4 (or else k has no generator in base k/2). - David Applegate, Jan 09 2022. See A349821 and A350607 for the k/2 and (k-2)/4 sequences.
It is not known if this sequence is infinite.
The eight terms 10 through 206 are all twice primes (cf. A349820).

Examples

			10 is a member because in base 2, 7=111, 7+3=10; in base 3, 7=21, 7+3=10; in base 4, 8=20, 8+2=10; in base 5, 7=12, 7+3=10; and in bases b >= 6, 5+5=10.
		

Crossrefs

For first differences see A349823.
This is the limiting row of A350601.

Extensions

More terms from Lars Blomberg, Oct 12 2015
More terms from David Applegate, Jan 02 2022

A349831 Even numbers in the intersection of A228082 and A349829.

Original entry on oeis.org

0, 2, 10, 12, 14, 16, 22, 24, 26, 28, 34, 36, 38, 40, 44, 50, 58, 60, 62, 66, 68, 70, 72, 74, 76, 82, 84, 92, 94, 96, 98, 106, 108, 110, 114, 118, 120, 122, 126, 132, 134, 136, 140, 146, 154, 156, 158, 162, 164, 170, 174, 176, 178, 186, 188, 190, 196, 198, 202, 204, 206, 210, 214, 216, 218, 222
Offset: 1

Views

Author

N. J. A. Sloane, Jan 07 2022

Keywords

Comments

Even numbers that are "generated" (in Kaprekar's sense) in both bases 2 and 4.

Crossrefs

A230624 is a subsequence.
A row of A350601.

A349832 Even numbers that are "generated" (in Kaprekar's sense) in all three bases 2, 4, and 6.

Original entry on oeis.org

0, 2, 10, 14, 16, 22, 24, 28, 34, 36, 38, 44, 50, 58, 60, 62, 66, 68, 72, 74, 76, 82, 84, 92, 94, 96, 98, 106, 108, 110, 118, 120, 122, 126, 132, 134, 136, 140, 146, 154, 156, 158, 162, 164, 170, 176, 178, 186, 196, 198, 202, 206, 210, 214, 216, 222, 228, 234, 238, 244, 246, 252, 256, 258, 260
Offset: 1

Views

Author

N. J. A. Sloane, Jan 07 2022

Keywords

Comments

Using Max Alekseyev's PARI "Gen" program (see A010061), we run
vector(500,k,length(Gen(k,2))),
vector(500,k,length(Gen(k,4))), and
vector(500,k,length(Gen(k,6)))
to find the numbers that are generated in bases 2, 4, and 6, and then take the even numbers that are common to all three lists.

Crossrefs

A230624 is a subsequence.
A row of A350601.

A349833 Even numbers that are "generated" (in Kaprekar's sense) in all four bases 2, 4, 6, and 8.

Original entry on oeis.org

0, 2, 10, 14, 22, 24, 28, 36, 38, 44, 50, 58, 60, 62, 66, 68, 74, 76, 82, 84, 92, 94, 96, 98, 106, 110, 118, 120, 122, 132, 134, 136, 140, 154, 156, 158, 162, 170, 176, 178, 186, 196, 198, 206, 210, 214, 216, 222, 228, 234, 244, 246, 252, 258, 260, 262, 264, 268, 274, 284, 286
Offset: 1

Views

Author

N. J. A. Sloane, Jan 07 2022

Keywords

Comments

Using Max Alekseyev's PARI "Gen" program (see A010061), we run
vector(500,k,length(Gen(k,2))),
vector(500,k,length(Gen(k,4))),
vector(500,k,length(Gen(k,6))),
vector(500,k,length(Gen(k,8))),
to find the numbers that are generated in bases 2, 4, 6, and 8, and then take the even numbers that are common to all four lists.

Crossrefs

A230624 is a subsequence.
A row of A350601.
Showing 1-5 of 5 results.