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 1-3 of 3 results.

A022795 Place where n-th 1 occurs in A023133.

Original entry on oeis.org

1, 5, 12, 22, 35, 51, 70, 92, 118, 147, 179, 214, 252, 293, 337, 385, 436, 490, 547, 607, 670, 736, 806, 879, 955, 1034, 1116, 1201, 1289, 1381, 1476, 1574, 1675, 1779, 1886, 1996, 2110, 2227, 2347, 2470, 2596, 2725, 2857, 2993, 3132, 3274
Offset: 1

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Keywords

Examples

			a(n) = 1 + Sum_{k=1..n-1} ceiling(r*k) where r=Pi. [_Benoit Cloitre_, Jan 24 2009]
		

Crossrefs

Cf. A023133.

Programs

A283944 Interspersion of the signature sequence of Pi (rectangular array by antidiagonals).

Original entry on oeis.org

1, 5, 2, 12, 7, 3, 22, 15, 9, 4, 35, 26, 18, 11, 6, 51, 40, 30, 21, 14, 8, 70, 57, 45, 34, 25, 17, 10, 92, 77, 63, 50, 39, 29, 20, 13, 118, 100, 84, 69, 56, 44, 33, 24, 16, 147, 127, 108, 91, 76, 62, 49, 38, 28, 19, 179, 157, 136, 116, 99, 83, 68, 55, 43, 32
Offset: 1

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Author

Clark Kimberling, Mar 26 2017

Keywords

Comments

Row n is the ordered sequence of numbers k such that A023133(k) = n. As a sequence, it is a permutation of the positive integers. This is a transposable interspersion; i.e., every row intersperses all other rows, and every column intersperses all other columns.

Examples

			Northwest corner:
1  5   12  22   35   51   70   92    118
2  7   15  26   40   57   77   100   127
3  9   18  30   45   63   84   108   136
4  11  21  34   50   69   91   115   145
6  14  25  39   56   76   99   125   155
8  17  29  44   62   83   107  134   165
		

Crossrefs

Programs

  • Mathematica
    r = Pi; z = 100;
    s[0] = 1; s[n_] := s[n] = s[n - 1] + 1 + Floor[n*r];
    u = Table[n + 1 + Sum[Floor[(n - k)/r], {k, 0, n}], {n, 0, z}] (* A022796, col 1 of A283944 *)
    v = Table[s[n], {n, 0, z}] (* A022795, row 1 of A283944 *)
    w[i_, j_] := u[[i]] + v[[j]] + (i - 1)*(j - 1) - 1;
    Grid[Table[w[i, j], {i, 1, 10}, {j, 1, 10}]] (* A283944, array*)
    Flatten[Table[w[k, n - k + 1], {n, 1, 20}, {k, 1, n}]] (* A283944, sequence *)
  • PARI
    \\ Produces the triangle when the array is read by antidiagonals
    r = Pi;
    z = 100;
    s(n) = if(n<1, 1, s(n - 1) + 1 + floor(n*r));
    p(n) = n + 1 + sum(k=0, n, floor((n - k)/r));
    u = v = vector(z + 1);
    for(n=1, 101, (v[n] = s(n - 1)));
    for(n=1, 101, (u[n] = p(n - 1)));
    w(i, j) = u[i] + v[j] + (i - 1) * (j - 1) - 1;
    tabl(nn) = {for(n=1, nn, for(k=1, n, print1(w(k, n - k + 1), ", "); ); print(); ); };
    tabl(10) \\ Indranil Ghosh, Mar 26 2017
    
  • Python
    # Produces the triangle when the array is read by antidiagonals
    import math
    from mpmath import *
    mp.dps = 100
    def s(n): return 1 if n<1 else s(n - 1) + 1 + int(math.floor(n*pi))
    def p(n): return n + 1 + sum([int(math.floor((n - k)/pi)) for k in range(0, n+1)])
    v=[s(n) for n in range(0, 101)]
    u=[p(n) for n in range(0, 101)]
    def w(i, j): return u[i - 1] + v[j - 1] + (i - 1) * (j - 1) - 1
    for n in range(1, 11):
        print([w(k, n - k + 1) for k in range(1, n + 1)]) # Indranil Ghosh, Mar 26 2017

A179547 Transcendental signature sequence of Pi.

Original entry on oeis.org

1, 2, 3, 4, 1, 5, 2, 6, 3, 7, 4, 1, 8, 5, 2, 9, 6, 3, 10, 7, 4, 1, 1, 11, 8, 5, 2, 2, 12, 9, 6, 3, 3, 13, 10, 7, 4, 1, 4, 14, 1, 11, 8, 5, 2, 5, 15, 2, 12, 9, 6, 3, 6, 16, 3, 13, 10, 7, 4, 1, 7, 17, 4, 14, 1, 11, 8, 5, 2, 8, 18, 5, 15, 2, 12, 9, 6, 3, 9, 19, 6, 16, 3, 13, 10, 7, 4, 1, 10, 20, 7, 17
Offset: 1

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Author

Kerry Mitchell, Jul 19 2010

Keywords

Comments

Let x be a transcendental number greater than 1. S1(x) is the standard signature sequence for an irrational number - sort y = a0 + a1x (for positive integers a0 and a1) and S1 is the sequence of a0 values. S2(x) is the sequence of a0's for sorted y = a0 + a1x + a2x^2, S3(x) is the a0 sequence for y = a0 + a1x + a2x^2 + a3x^3, etc. The transcendental signature sequence is the limit of Sn(x) as n approaches infinity.

Crossrefs

Cf. A023133 (signature sequence of Pi).
Showing 1-3 of 3 results.