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 1-4 of 4 results.

A103615 Number of zeros in A103542(n) (binary equivalent of A102370(n)).

Original entry on oeis.org

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

Views

Author

Philippe Deléham, Mar 31 2005

Keywords

Examples

			The sequence has a natural decomposition into blocks (see the paper): 1; 0; 1, 1, 2; 0, 2, 2, 3, 1, 1, 1; 2, 1, 3, 3, 4, 2, 2, 2, 3, 0, 2, 2, 3, 1, 1; 1, 3, ...
		

Crossrefs

Programs

  • Maple
    A023416 := proc(n) local digs : digs := convert(n,base,2) : if nops(digs) = 0 then 1: else add(1-j,j=digs) : fi : end: ili := readline("b102370.txt") : while ili <> 0 do na := sscanf(ili,"%d %d") : na := A023416(op(2,na)) ; printf("%d, ",na) ; ili := readline("b102370.txt") : od: # R. J. Mathar, Aug 10 2007

Formula

a(n) = A023416(A102370(n)). - R. J. Mathar, Aug 10 2007

Extensions

More terms from R. J. Mathar, Aug 10 2007

A105104 Write A102370 in binary (A103542), read backwards, omit leading zeros, convert to base 10.

Original entry on oeis.org

0, 3, 3, 5, 1, 15, 5, 9, 1, 13, 7, 11, 7, 29, 9, 17, 1, 25, 13, 21, 5, 31, 11, 19, 3, 27, 15, 47, 13, 57, 17, 33, 1, 49, 25, 41, 9, 61, 21, 37, 5, 53, 29, 45, 15, 59, 19, 35, 3, 51, 27, 43, 11, 63, 23, 39, 7, 55, 63, 93, 25, 113, 33, 65, 1, 97, 49, 81, 17, 121, 41, 73
Offset: 0

Views

Author

N. J. A. Sloane, Apr 30 2005

Keywords

Comments

Similar to A102370, but read diagonals in reverse direction.

Crossrefs

Programs

  • PARI
    a1(n) = fromdigits(Vecrev(binary(n)), 2); \\ A030101
    a0(n) = if( n<1, 0, sum(k=0, length(binary(n)), bitand(n + k, 2^k))); \\ A102370
    a(n) = a1(a0(n)); \\ Michel Marcus, Apr 09 2022

Formula

a(n) = A030101(A102370(n)). - Philippe Deléham, Nov 11 2007

Extensions

More terms from Philippe Deléham, Nov 11 2007
a(46)=19 inserted and more terms from Georg Fischer, Apr 08 2022

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

Views

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

A103863 Hamming distance between n and A102370(n) (in binary).

Original entry on oeis.org

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

Views

Author

Philippe Deléham, Mar 31 2005

Keywords

Comments

The Hamming distance between two strings of the same length is the number of places where they differ. - Robert G. Wilson v, Apr 12 2005

References

  • F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier/North Holland, 1978, p. 8.

Crossrefs

Programs

  • 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]; hammingdistance[n_] := Count[ IntegerDigits[ BitXor[n, f[n] + n], 2], 1]; Table[ hammingdistance[n], {n, 0, 104}] (* Robert G. Wilson v, Apr 12 2005 *)

Formula

a(A104235(n)) = 0.

Extensions

More terms from Robert G. Wilson v, Apr 12 2005
Showing 1-4 of 4 results.