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.

A105031 Binary equivalents of A103185.

Original entry on oeis.org

0, 1, 10, 1, 0, 101, 10, 1, 0, 1, 10, 1, 1000, 101, 10, 1, 0, 1, 10, 1, 0, 101, 10, 1, 0, 1, 10, 10001, 1000, 101, 10, 1, 0, 1, 10, 1, 0, 101, 10, 1, 0, 1, 10, 1, 1000, 101, 10, 1, 0, 1, 10, 1, 0, 101, 10, 1, 0, 1, 100010, 10001, 1000, 101, 10, 1, 0, 1, 10, 1, 0, 101, 10, 1, 0, 1, 10
Offset: 0

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Author

Keywords

Crossrefs

Extensions

More terms from Benoit Cloitre, Apr 04 2005

A105023 a(n) = A102370(n) - n. Or, 2*A103185(n).

Original entry on oeis.org

0, 2, 4, 2, 0, 10, 4, 2, 0, 2, 4, 2, 16, 10, 4, 2, 0, 2, 4, 2, 0, 10, 4, 2, 0, 2, 4, 34, 16, 10, 4, 2, 0, 2, 4, 2, 0, 10, 4, 2, 0, 2, 4, 2, 16, 10, 4, 2, 0, 2, 4, 2, 0, 10, 4, 2, 0, 2, 68, 34, 16, 10, 4, 2, 0, 2, 4, 2, 0, 10, 4, 2, 0, 2, 4, 2, 16, 10, 4, 2, 0, 2, 4, 2, 0, 10, 4, 2, 0, 2, 4, 34, 16, 10, 4
Offset: 0

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Author

N. J. A. Sloane, Apr 03 2005

Keywords

Comments

When written in base 2 as a right justified table, columns have periods 1, 2, 4, 8, ... - Philippe Deléham, Apr 21 2005

Examples

			Has a natural decomposition into blocks: 0; 2; 4, 2, 0; 10, 4, 2, 0, 2, 4, 2; 16, 10, 4, 2, 0, 2, 4, 2, 0, 10, 4, 2, 0, 2, 4; 34, 16, 10, 4, ... where the leading term in each block is given by A105024.
		

Crossrefs

Programs

  • Maple
    s:= proc (n) local t1, l; t1 := 0; for l to n do if `mod`(n+l,2^l) = 0 then t1 := t1+2^l end if end do; t1 end proc;

Formula

a(n) = Sum_{ k >= 1 such that n + k == 0 mod 2^k } 2^k.

A102370 "Sloping binary numbers": write numbers in binary under each other (right-justified), read diagonals in upward direction, convert to decimal.

Original entry on oeis.org

0, 3, 6, 5, 4, 15, 10, 9, 8, 11, 14, 13, 28, 23, 18, 17, 16, 19, 22, 21, 20, 31, 26, 25, 24, 27, 30, 61, 44, 39, 34, 33, 32, 35, 38, 37, 36, 47, 42, 41, 40, 43, 46, 45, 60, 55, 50, 49, 48, 51, 54, 53, 52, 63, 58, 57, 56, 59, 126, 93, 76, 71, 66, 65, 64, 67, 70, 69
Offset: 0

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Author

Philippe Deléham, Feb 13 2005

Keywords

Comments

All terms are distinct, but certain terms (see A102371) are missing. But see A103122.
Trajectory of 1 is 1, 3, 5, 15, 17, 19, 21, 31, 33, ..., see A103192.

Examples

			........0
........1
.......10
.......11
......100
......101
......110
......111
.....1000
.........
The upward-sloping diagonals are:
0
11
110
101
100
1111
1010
.......
giving 0, 3, 6, 5, 4, 15, 10, ...
The sequence has a natural decomposition into blocks (see the paper): 0; 3; 6, 5, 4; 15, 10, 9, 8, 11, 14, 13; 28, 23, 18, 17, 16, 19, 22, 21, 20, 31, 26, 25, 24, 27, 30; 61, ...
Reading the array of binary numbers along diagonals with slope 1 gives this sequence, slope 2 gives A105085, slope 0 gives A001477 and slope -1 gives A105033.
		

Crossrefs

Related sequences (1): A103542 (binary version), A102371 (complement), A103185, A103528, A103529, A103530, A103318, A034797, A103543, A103581, A103582, A103583.
Related sequences (2): A103584, A103585, A103586, A103587, A103127, A103192 (trajectory of 1), A103122, A103588, A103589, A103202 (sorted), A103205 (base 10 version).
Related sequences (3): A103747 (trajectory of 2), A103621, A103745, A103615, A103842, A103863, A104234, A104235, A103813, A105023, A105024, A105025, A105026, A105027, A105028.
Related sequences (4): A105029, A105030, A105031, A105032, A105033, A105034, A105035, A105108.

Programs

  • Haskell
    a102370 n = a102370_list !! n
    a102370_list = 0 : map (a105027 . toInteger) a062289_list
    -- Reinhard Zumkeller, Jul 21 2012
    
  • Maple
    A102370:=proc(n) local t1,l; t1:=n; for l from 1 to n do if n+l mod 2^l = 0 then t1:=t1+2^l; fi; od: t1; end;
  • Mathematica
    f[n_] := Block[{k = 1, s = 0, l = Max[2, Floor[Log[2, n + 1] + 2]]}, While[k < l, If[ Mod[n + k, 2^k] == 0, s = s + 2^k]; k++ ]; s]; Table[ f[n] + n, {n, 0, 71}] (* Robert G. Wilson v, Mar 21 2005 *)
  • PARI
    A102370(n)=n-1+sum(k=0,ceil(log(n+1)/log(2)),if((n+k)%2^k,0,2^k)) \\ Benoit Cloitre, Mar 20 2005
    
  • PARI
    {a(n) = if( n<1, 0, sum( k=0, length( binary( n)), bitand( n + k, 2^k)))} /* Michael Somos, Mar 26 2012 */
    
  • Python
    def a(n): return 0 if n<1 else sum([(n + k)&(2**k) for k in range(len(bin(n)[2:]) + 1)]) # Indranil Ghosh, May 03 2017

Formula

a(n) = n + Sum_{ k >= 1 such that n + k == 0 mod 2^k } 2^k. (Cf. A103185.) In particular, a(n) >= n. - N. J. A. Sloane, Mar 18 2005
a(n) = A105027(A062289(n)) for n > 0. - Reinhard Zumkeller, Jul 21 2012

Extensions

More terms from Benoit Cloitre, Mar 20 2005

A104234 Number of k >= 1 such that k+n == 0 mod 2^k.

Original entry on oeis.org

0, 1, 1, 1, 0, 2, 1, 1, 0, 1, 1, 1, 1, 2, 1, 1, 0, 1, 1, 1, 0, 2, 1, 1, 0, 1, 1, 2, 1, 2, 1, 1, 0, 1, 1, 1, 0, 2, 1, 1, 0, 1, 1, 1, 1, 2, 1, 1, 0, 1, 1, 1, 0, 2, 1, 1, 0, 1, 2, 2, 1, 2, 1, 1, 0, 1, 1, 1, 0, 2, 1, 1, 0, 1, 1, 1, 1, 2, 1, 1, 0, 1, 1, 1, 0, 2, 1, 1, 0, 1, 1, 2, 1, 2, 1, 1, 0, 1, 1, 1, 0, 2, 1, 1, 0, 1
Offset: 0

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Author

N. J. A. Sloane, Apr 02 2005

Keywords

Comments

Number of terms in the summation in the formula for A102370(n).
Also, a(n) is the number of 1's in (A103185(n) written in base 2).

Crossrefs

Cf. A102370, A103185, A105035 (records).

Programs

  • Maple
    f:=proc(n) local t1,l; t1:=0; for l from 1 to n do if n+l mod 2^l = 0 then t1:=t1+1; fi; od: t1; end;

Formula

a(2^k + y) = a(y) + 1 if y = 2^k - k - 1, = a(y) otherwise (where 0 <= y <= 2^k - 1).

A103745 a(n) = (A102371(n) + n)/2.

Original entry on oeis.org

1, 2, 5, 8, 17, 34, 65, 128, 257, 514, 1029, 2048, 4097, 8194, 16385, 32768, 65537, 131074, 262149, 524296, 1048577, 2097154, 4194305, 8388608, 16777217, 33554434, 67108869, 134217728, 268435457, 536870914, 1073741825, 2147483648, 4294967297, 8589934594, 17179869189
Offset: 1

Views

Author

Philippe Deléham, Mar 26 2005

Keywords

Comments

Values of A103185 (first zero omitted) which are >= a new power of 2 . The initial values of A103185 are 0*, 1*, 2*, 1, 0, 5*, 2, 1, 0, 1, 2, 1, 8*, 5, 2, 1, ... and the starred terms are those which exceed the next power of 2 . Their indices (except for the zero term) are given by A000325.

Crossrefs

Programs

  • PARI
    a(n) = 2^(n-1) + sum(k = 1, n-1, if ((n % 2^k) == k, 2^(k-1))); \\ Michel Marcus, May 06 2020

Formula

a(n) = Sum_{ k>= 1, k == n (mod 2^k) } 2^(k-1). - N. J. A. Sloane and David Applegate, Mar 22 2005
a(n) = A103528(n) + 2^(n-1).

Extensions

a(27) corrected and more terms from Michel Marcus, May 06 2020
Showing 1-5 of 5 results.