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.

A348473 a(n) = Sum_{k=1..A003056(n)} 2^(T(n,k)-1), where T(n,k) = k-th term in row n of A235791.

Original entry on oeis.org

1, 2, 5, 9, 18, 35, 69, 133, 266, 523, 1043, 2069, 4133, 8230, 16459, 32843, 65675, 131221, 262421, 524566, 1049127, 2097707, 4195371, 8389707, 16779341, 33556565, 67113110, 134221975, 268443799, 536879403, 1073758507, 2147500331, 4295000621, 8589967949, 17179935318
Offset: 1

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Author

Michael De Vlieger, Oct 19 2021

Keywords

Comments

Decimal value of binary compactification of A235791.

Examples

			Row 3 of A235791 contains {3,1}, thus, a(3) = 2^(3-1) + 2(1-1)= 2^2 + 2^0 = 4+1 = 5.
Omar E. Pol's diagram of rows of A235791:
.                                    y         a(n)_2          a(n)
Row                                 _|    -------------------------
1                                 _|1| ->                1 =     1
2                               _|2 _| ->               10 =     2
3                             _|3  |1| ->              101 =     5
4                           _|4   _|1| ->             1001 =     9
5                         _|5    |2 _| ->            10010 =    18
6                       _|6     _|2|1| ->           100011 =    35
7                     _|7      |3  |1| ->          1000101 =    69
8                   _|8       _|3 _|1| ->         10000101 =   133
9                 _|9        |4  |2 _| ->        100001010 =   266
10              _|10        _|4  |2|1| ->       1000001011 =   523
11            _|11         |5   _|2|1| ->      10000010011 =  1043
12          _|12          _|5  |3  |1| ->     100000010101 =  2069
13        _|13           |6    |3 _|1| ->    1000000100101 =  4133
14      _|14            _|6   _|3|2 _| ->   10000000100110 =  8230
15    _|15             |7    |4  |2|1| ->  100000001001011 = 16459
16  _|16              _|7    |4  |2|1| -> 1000000001001011 = 32843
...
		

Crossrefs

Programs

  • Mathematica
    Table[Total@ Array[2^(-1 + Ceiling[(n + 1)/# - (# + 1)/2]) &, Floor[(Sqrt[8 n + 1] - 1)/2]], {n, 35}]
    (* Regenerate k rows of A235791 using the b-file *)
    With[{k = 120}, MapIndexed[1 + First[#2] - Position[IntegerDigits[#1, 2], 1][[All, 1]] &, Import["https://oeis.org/A348473/b348473.txt", "Data"][[1 ;; k, -1]]]] (* Michael De Vlieger, Oct 21 2021 *)