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 1-7 of 7 results.

A372287 Array read by upward antidiagonals: A(n, k) = A371092(A372283(n, k)), n,k >= 1.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 2, 1, 1, 1, 3, 2, 3, 1, 1, 1, 1, 3, 3, 1, 1, 1, 1, 1, 3, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 6, 3, 1, 1, 1, 1, 1, 1, 1, 9, 1, 5, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 6, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 9, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5, 7
Offset: 1

Views

Author

Antti Karttunen, Apr 28 2024

Keywords

Comments

A(n, k) gives the column index of A372282(n, k) [or equally, of A372283(n, k)] in array A257852.
Collatz conjecture is equal to the claim that in each column 1 will eventually appear.

Examples

			Array begins:
n\k| 1  2  3  4  5  6  7  8  9 10 11 12 13  14 15  16 17 18 19  20
---+---------------------------------------------------------------
1  | 1, 1, 1, 2, 2, 3, 1, 4, 3, 5, 1, 6, 4,  7, 2,  8, 5, 9, 2, 10,
2  | 1, 1, 1, 3, 2, 3, 1, 6, 1, 2, 1, 9, 5,  6, 3, 12, 4, 1, 2, 15,
3  | 1, 1, 1, 3, 3, 1, 1, 9, 1, 3, 1, 1, 2,  8, 3, 18, 5, 1, 3, 12,
4  | 1, 1, 1, 1, 3, 1, 1, 1, 1, 3, 1, 1, 3, 12, 1, 27, 2, 1, 3, 17,
5  | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 18, 1, 21, 3, 1, 1,  4,
6  | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 27, 1, 16, 3, 1, 1,  5,
7  | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 21, 1, 23, 1, 1, 1,  2,
8  | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 16, 1, 18, 1, 1, 1,  3,
9  | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 23, 1, 26, 1, 1, 1,  3,
10 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 18, 1, 39, 1, 1, 1,  1,
11 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 26, 1, 30, 1, 1, 1,  1,
12 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 39, 1, 44, 1, 1, 1,  1,
13 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 30, 1, 66, 1, 1, 1,  1,
14 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 44, 1, 99, 1, 1, 1,  1,
15 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 66, 1, 75, 1, 1, 1,  1,
16 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 99, 1, 28, 1, 1, 1,  1,
17 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 75, 1, 42, 1, 1, 1,  1,
18 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 28, 1, 63, 1, 1, 1,  1,
19 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 42, 1, 48, 1, 1, 1,  1,
20 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 63, 1, 71, 1, 1, 1,  1,
		

Crossrefs

Cf. also A371097 (array giving every fourth column, 1, 5, 9, ...), A371103 (array giving every even numbered column), also array A371101.

Programs

  • PARI
    up_to = 105;
    A000265(n) = (n>>valuation(n,2));
    A371092(n) = floor((A000265(1+(3*n))+5)/6);
    R(n) = { n = 1+3*n; n>>valuation(n, 2); };
    A372283sq(n,k) = if(1==n,2*k-1,R(A372283sq(n-1,k)));
    A372287sq(n,k) = A371092(A372283sq(n,k));
    A372287list(up_to) = { my(v = vector(up_to), i=0); for(a=1,oo, for(col=1,a, i++; if(i > up_to, return(v)); v[i] = A372287sq((a-(col-1)),col))); (v); };
    v372287 = A372287list(up_to);
    A372287(n) = v372287[n];

Formula

A(n, k) = A371092(A372282(n,k)) = A371092(A372283(n,k)).

A371101 Array A read by upward antidiagonals in which the entry A(n,k) = A371092(A371100(n, k)), n,k >= 1.

Original entry on oeis.org

1, 1, 3, 1, 2, 3, 1, 3, 1, 6, 1, 2, 3, 5, 2, 1, 3, 1, 6, 4, 9, 1, 2, 3, 5, 2, 8, 6, 1, 3, 1, 6, 4, 9, 2, 12, 1, 2, 3, 5, 2, 8, 6, 11, 1, 1, 3, 1, 6, 4, 9, 2, 12, 7, 15, 1, 2, 3, 5, 2, 8, 6, 11, 1, 14, 9, 1, 3, 1, 6, 4, 9, 2, 12, 7, 15, 4, 18, 1, 2, 3, 5, 2, 8, 6, 11, 1, 14, 9, 17, 5, 1, 3, 1, 6, 4, 9, 2, 12, 7, 15, 4, 18, 10, 21
Offset: 1

Views

Author

Antti Karttunen, Apr 19 2024

Keywords

Comments

A(n, k) gives the column index of A371100(n, k) in array A257852.

Examples

			The array begins:
n\k|  1  2  3  4  5  6  7   8  9  10 11  12  13  14  15  16  17  18
---+--------------------------------------------------------------------
1  |  1, 3, 3, 6, 2, 9, 6, 12, 1, 15, 9, 18,  5, 21, 12, 24,  4, 27, ...
2  |  1, 2, 1, 5, 4, 8, 2, 11, 7, 14, 4, 17, 10, 20,  1, 23, 13, 26, ...
3  |  1, 3, 3, 6, 2, 9, 6, 12, 1, 15, 9, 18,  5, 21, 12, 24,  4, 27, ...
4  |  1, 2, 1, 5, 4, 8, 2, 11, 7, 14, 4, 17, 10, 20,  1, 23, 13, 26, ...
5  |  1, 3, 3, 6, 2, 9, 6, 12, 1, 15, 9, 18,  5, 21, 12, 24,  4, 27, ...
6  |  1, 2, 1, 5, 4, 8, 2, 11, 7, 14, 4, 17, 10, 20,  1, 23, 13, 26, ...
7  |  1, 3, 3, 6, 2, 9, 6, 12, 1, 15, 9, 18,  5, 21, 12, 24,  4, 27, ...
8  |  1, 2, 1, 5, 4, 8, 2, 11, 7, 14, 4, 17, 10, 20,  1, 23, 13, 26, ...
...
		

Crossrefs

Programs

  • PARI
    up_to = 105;
    A000265(n) = (n>>valuation(n,2));
    A371092(n) = floor((A000265(1+(3*n))+5)/6);
    A371100sq(n,k) = 4^n*(6*k - 3 - 2*(-1)^n) + (4^n - 1)/3;
    A371101sq(n,k) = A371092(A371100sq(n,k));
    A371101list(up_to) = { my(v = vector(up_to), i=0); for(a=1,oo, for(col=1,a, i++; if(i > up_to, return(v)); v[i] = A371101sq((a-(col-1)),col))); (v); };
    v371101 = A371101list(up_to);
    A371101(n) = v371101[n];

Formula

A(n, k) = A371092(A371100(n, k)).
A(n, k) = A(n+2, k).

A371103 Array A read by upward antidiagonals in which the entry A(n,k) in row n and column k is defined by A(n, k) = A371092(A371102(n, k)), n,k >= 1.

Original entry on oeis.org

1, 1, 2, 1, 3, 3, 1, 3, 3, 4, 1, 1, 1, 6, 5, 1, 1, 1, 9, 2, 6, 1, 1, 1, 1, 3, 9, 7, 1, 1, 1, 1, 3, 1, 6, 8, 1, 1, 1, 1, 1, 1, 8, 12, 9, 1, 1, 1, 1, 1, 1, 12, 18, 1, 10, 1, 1, 1, 1, 1, 1, 18, 27, 1, 15, 11, 1, 1, 1, 1, 1, 1, 27, 21, 1, 12, 9, 12, 1, 1, 1, 1, 1, 1, 21, 16, 1, 17, 7, 18, 13, 1, 1, 1, 1, 1, 1, 16, 23, 1, 4, 2, 27, 5, 14
Offset: 1

Views

Author

Antti Karttunen, Apr 21 2024

Keywords

Comments

A(n, k) gives the column index of A371102(n, k) in array A257852.

Examples

			Array begins:
n\k| 1  2   3   ...
---+--------------------------------------------------------------------
1  | 1, 2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17,
2  | 1, 3,  3,  6,  2,  9,  6, 12,  1, 15,  9, 18,  5, 21, 12, 24,  4,
3  | 1, 3,  1,  9,  3,  1,  8, 18,  1, 12,  7, 27,  2,  8, 17, 36,  5,
4  | 1, 1,  1,  1,  3,  1, 12, 27,  1, 17,  2, 21,  3, 12,  4, 54,  2,
5  | 1, 1,  1,  1,  1,  1, 18, 21,  1,  4,  2, 16,  3, 18,  5, 81,  3,
6  | 1, 1,  1,  1,  1,  1, 27, 16,  1,  5,  3, 23,  1, 27,  2, 16,  3,
7  | 1, 1,  1,  1,  1,  1, 21, 23,  1,  2,  3, 18,  1, 21,  3, 23,  1,
8  | 1, 1,  1,  1,  1,  1, 16, 18,  1,  3,  1, 26,  1, 16,  3, 18,  1,
9  | 1, 1,  1,  1,  1,  1, 23, 26,  1,  3,  1, 39,  1, 23,  1, 26,  1,
10 | 1, 1,  1,  1,  1,  1, 18, 39,  1,  1,  1, 30,  1, 18,  1, 39,  1,
11 | 1, 1,  1,  1,  1,  1, 26, 30,  1,  1,  1, 44,  1, 26,  1, 30,  1,
12 | 1, 1,  1,  1,  1,  1, 39, 44,  1,  1,  1, 66,  1, 39,  1, 44,  1,
13 | 1, 1,  1,  1,  1,  1, 30, 66,  1,  1,  1, 99,  1, 30,  1, 66,  1,
14 | 1, 1,  1,  1,  1,  1, 44, 99,  1,  1,  1, 75,  1, 44,  1, 99,  1,
15 | 1, 1,  1,  1,  1,  1, 66, 75,  1,  1,  1, 28,  1, 66,  1, 75,  1,
16 | 1, 1,  1,  1,  1,  1, 99, 28,  1,  1,  1, 42,  1, 99,  1, 28,  1,
17 | 1, 1,  1,  1,  1,  1, 75, 42,  1,  1,  1, 63,  1, 75,  1, 42,  1,
18 | 1, 1,  1,  1,  1,  1, 28, 63,  1,  1,  1, 48,  1, 28,  1, 63,  1,
19 | 1, 1,  1,  1,  1,  1, 42, 48,  1,  1,  1, 71,  1, 42,  1, 48,  1,
20 | 1, 1,  1,  1,  1,  1, 63, 71,  1,  1,  1, 54,  1, 63,  1, 71,  1,
21 | 1, 1,  1,  1,  1,  1, 48, 54,  1,  1,  1, 80,  1, 48,  1, 54,  1,
		

Crossrefs

Cf. A000027 (row 1), A257852, A371092, A371102.
Cf. also arrays A371097, A371101.

Programs

A371097 Array A read by upward antidiagonals in which the entry A(n,k) in row n and column k is defined by A(n, k) = A371092(A371095(n, k)), n,k >= 1.

Original entry on oeis.org

1, 1, 2, 1, 2, 3, 1, 3, 1, 4, 1, 3, 1, 5, 5, 1, 1, 1, 2, 4, 6, 1, 1, 1, 3, 5, 8, 7, 1, 1, 1, 3, 2, 12, 2, 8, 1, 1, 1, 1, 3, 18, 2, 11, 9, 1, 1, 1, 1, 3, 27, 3, 9, 7, 10, 1, 1, 1, 1, 1, 21, 3, 7, 2, 14, 11, 1, 1, 1, 1, 1, 16, 1, 2, 2, 21, 4, 12, 1, 1, 1, 1, 1, 23, 1, 2, 3, 8, 6, 17, 13, 1, 1, 1, 1, 1, 18, 1, 3, 3, 12, 9, 4, 10, 14
Offset: 1

Views

Author

Antti Karttunen, Apr 21 2024

Keywords

Comments

A(n, k) gives the column index of A371095(n, k) [or equally, of A371096(n, k)] in array A257852.

Examples

			Array begins:
n\k| 1  2  3  ...
---+--------------------------------------------------------------
1  | 1, 2, 3, 4, 5,  6, 7,  8, 9, 10, 11, 12, 13, 14, 15,  16, 17,
2  | 1, 2, 1, 5, 4,  8, 2, 11, 7, 14,  4, 17, 10, 20,  1,  23, 13,
3  | 1, 3, 1, 2, 5, 12, 2,  9, 2, 21,  6,  4, 14, 30,  1,  18, 10,
4  | 1, 3, 1, 3, 2, 18, 3,  7, 2,  8,  9,  5, 21, 45,  1,  26, 14,
5  | 1, 1, 1, 3, 3, 27, 3,  2, 3, 12,  1,  2,  8, 17,  1,  39, 21,
6  | 1, 1, 1, 1, 3, 21, 1,  2, 3, 18,  1,  3, 12,  4,  1,  30,  8,
7  | 1, 1, 1, 1, 1, 16, 1,  3, 1, 27,  1,  3, 18,  5,  1,  44, 12,
8  | 1, 1, 1, 1, 1, 23, 1,  3, 1, 21,  1,  1, 27,  2,  1,  66, 18,
9  | 1, 1, 1, 1, 1, 18, 1,  1, 1, 16,  1,  1, 21,  3,  1,  99, 27,
10 | 1, 1, 1, 1, 1, 26, 1,  1, 1, 23,  1,  1, 16,  3,  1,  75, 21,
11 | 1, 1, 1, 1, 1, 39, 1,  1, 1, 18,  1,  1, 23,  1,  1,  28, 16,
12 | 1, 1, 1, 1, 1, 30, 1,  1, 1, 26,  1,  1, 18,  1,  1,  42, 23,
13 | 1, 1, 1, 1, 1, 44, 1,  1, 1, 39,  1,  1, 26,  1,  1,  63, 18,
14 | 1, 1, 1, 1, 1, 66, 1,  1, 1, 30,  1,  1, 39,  1,  1,  48, 26,
15 | 1, 1, 1, 1, 1, 99, 1,  1, 1, 44,  1,  1, 30,  1,  1,  71, 39,
16 | 1, 1, 1, 1, 1, 75, 1,  1, 1, 66,  1,  1, 44,  1,  1,  54, 30,
17 | 1, 1, 1, 1, 1, 28, 1,  1, 1, 99,  1,  1, 66,  1,  1,  80, 44,
18 | 1, 1, 1, 1, 1, 42, 1,  1, 1, 75,  1,  1, 99,  1,  1, 120, 66,
19 | 1, 1, 1, 1, 1, 63, 1,  1, 1, 28,  1,  1, 75,  1,  1, 180, 99,
20 | 1, 1, 1, 1, 1, 48, 1,  1, 1, 42,  1,  1, 28,  1,  1, 270, 75,
21 | 1, 1, 1, 1, 1, 71, 1,  1, 1, 63,  1,  1, 42,  1,  1, 405, 28,
		

Crossrefs

Cf. also arrays A371101, A371103.

Programs

  • PARI
    up_to = 105;
    A000265(n) = (n>>valuation(n,2));
    A371092(n) = floor((A000265(1+(3*n))+5)/6);
    R(n) = { n = 1+3*n; n>>valuation(n, 2); };
    A371095sq(n,k) = if(1==n,8*k-7,R(A371095sq(n-1,k)));
    A371097sq(n,k) = A371092(A371095sq(n,k));
    A371097list(up_to) = { my(v = vector(up_to), i=0); for(a=1,oo, for(col=1,a, i++; if(i > up_to, return(v)); v[i] = A371097sq((a-(col-1)),col))); (v); };
    v371097 = A371097list(up_to);
    A371097(n) = v371097[n];

Formula

A(n, k) = A371092(A371095(n, k)) = A371092(A371096(n, k)).

A372445 a(n) = A371092(A372443(n)).

Original entry on oeis.org

7, 6, 8, 12, 18, 27, 21, 16, 23, 18, 26, 39, 30, 44, 66, 99, 75, 28, 42, 63, 48, 71, 54, 80, 120, 180, 270, 405, 152, 228, 342, 513, 97, 73, 55, 11, 4, 6, 9, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
Offset: 0

Views

Author

Antti Karttunen, May 01 2024

Keywords

Comments

a(n) gives the column index of A372443(n), or equally, of A372444(n) in array A257852.

Crossrefs

Column 14 of A372287, column 7 of A371103.

Programs

Formula

a(n) = A371092(A372443(n)) = A371092(A372444(n)).

A257852 Array A read by upward antidiagonals in which the entry A(n,k) in row n and column k is defined by A(n,k) = (2^n*(6*k - 3 - 2*(-1)^n) - 1)/3, n,k >= 1.

Original entry on oeis.org

3, 1, 7, 13, 9, 11, 5, 29, 17, 15, 53, 37, 45, 25, 19, 21, 117, 69, 61, 33, 23, 213, 149, 181, 101, 77, 41, 27, 85, 469, 277, 245, 133, 93, 49, 31, 853, 597, 725, 405, 309, 165, 109, 57, 35, 341, 1877, 1109, 981, 533, 373, 197, 125, 65, 39
Offset: 1

Views

Author

L. Edson Jeffery, Jul 12 2015

Keywords

Comments

Sequence is a permutation of the odd natural numbers.
Let N_1 denote the set of odd natural numbers, and let |y|_2 denote 2-adic valuation of y. Define the map F : N_1 -> N_1 by F(x) = (3*x + 1)/2^|3*x+1|_2 (cf. A075677). Then row n of A is the set of all x in N_1 for which |3*x + 1|_2 = A371093(x) = n. Hence F(A(n,k)) = 6*k - 3 - 2*(-1)^n.

Examples

			From _Ruud H.G. van Tol_, Oct 17 2023, corrected and extended by _Antti Karttunen_, Apr 18 2024: (Start)
Array A begins:
n\k|   1|   2|   3|   4|   5|   6|   7|   8| ...
---+---------------------------------------------
1  |   3,   7,  11,  15,  19,  23,  27,  31, ...
2  |   1,   9,  17,  25,  33,  41,  49,  57, ...
3  |  13,  29,  45,  61,  77,  93, 109, 125, ...
4  |   5,  37,  69, 101, 133, 165, 197, 229, ...
5  |  53, 117, 181, 245, 309, 373, 437, 501, ...
6  |  21, 149, 277, 405, 533, 661, 789, 917, ...
... (End)
		

Crossrefs

Cf. A006370, A075677, A096773 (after its initial 0, column 1 of this array).
Cf. A004767, A017077, A082285, A238477 (rows 1-4).
Cf. A371092, A371093 (column and row indices for odd numbers).

Programs

  • Mathematica
    (* Array: *)
    Grid[Table[(2^n*(6*k - 3 - 2*(-1)^n) - 1)/3, {n, 10}, {k, 10}]]
    (* Array antidiagonals flattened: *)
    Flatten[Table[(2^(n - k + 1)*(6*k - 3 - 2*(-1)^(n - k + 1)) - 1)/ 3, {n, 10}, {k, n}]]
  • PARI
    up_to = 105;
    A257852sq(n,k) = ((2^n * (6*k - 3 - 2*(-1)^n) - 1)/3);
    A257852list(up_to) = { my(v = vector(up_to), i=0); for(a=1,oo, for(col=1,a, i++; if(i > up_to, return(v)); v[i] = A257852sq((a-(col-1)),col))); (v); };
    v257852 = A257852list(up_to);
    A257852(n) = v257852[n]; \\ Antti Karttunen, Apr 18 2024

Formula

From Ruud H.G. van Tol, Oct 17 2023: (Start)
A(n,k+1) = A(n,k) + 2^(n+1).
A(n+2,k) = A(n,k)*4 + 1.
A(1,k) = A004767(k-1).
A(2,k) = A017077(k-1).
A(3,k) = A082285(k-1).
A(4,k) = A238477(k). (End)
For all odd positive numbers n, A(A371093(n), A371092(n)) = n. - Antti Karttunen, Apr 24 2024

A371093 a(n) is the 2-adic valuation of 3n+1.

Original entry on oeis.org

0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 8, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2
Offset: 0

Views

Author

Antti Karttunen, Apr 19 2024

Keywords

Comments

When a(n) is applied to square array A257852 we obtain square array A004736, or in other words, a(n) applied to any odd number gives the index of the row where it is located in array A257852.
See further comments in A087230.
The asymptotic density of the occurrences of k = 0, 1, 2, ... is 1/2^(k+1). The asymptotic mean of this sequence is 1. - Amiram Eldar, May 28 2024

Crossrefs

Bisections: A000004, A087230.
Cf. also A371092.

Programs

  • Mathematica
    Table[IntegerExponent[3*n+1, 2], {n, 0, 105}] (* James C. McMahon, Apr 21 2024 *)
  • PARI
    A371093(n) = valuation(1+3*n,2);
    
  • Python
    def A371093(n): return ((m:=3*n) & ~(m+1)).bit_length() # Chai Wah Wu, Apr 20 2024

Formula

a(n) = A007814(A016777(n)).
For all n >= 0, A067745(1+n) = A016777(n) / 2^a(n).
G.f.: Sum_{k>=1} k*x^(-1/3 + (-2)^(k + 1)/3 + 2^k)/(1 - x^(2^(k + 1))). - Miles Wilson, Sep 30 2024
Showing 1-7 of 7 results.