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.

Previous Showing 11-20 of 25 results. Next

A246830 T(n,k) is the concatenation of n-k and n+k in binary; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

0, 3, 2, 10, 7, 4, 15, 20, 13, 6, 36, 29, 22, 15, 8, 45, 38, 31, 40, 25, 10, 54, 47, 72, 57, 42, 27, 12, 63, 104, 89, 74, 59, 44, 29, 14, 136, 121, 106, 91, 76, 61, 46, 31, 16, 153, 138, 123, 108, 93, 78, 63, 80, 49, 18, 170, 155, 140, 125, 110, 95, 144, 113, 82, 51, 20
Offset: 0

Views

Author

Alois P. Heinz, Sep 04 2014

Keywords

Examples

			Triangle T(n,k) begins:
   0
   3  2
  10  7  4
  15 20 13  6
  36 29 22 15  8
  45 38 31 40 25 10
  54 47 72 57 42 27 12
Triangle T(n,k) written in binary (with | denoting the concat operation) begins:
     |0
    1|1      |10
   10|10    1|11     |100
   11|11   10|100   1|101    |110
  100|100  11|101  10|110   1|111    |1000
  101|101 100|110  11|111  10|1000  1|1001  |1010
  110|110 101|111 100|1000 11|1001 10|1010 1|1011 |1100
		

Crossrefs

Column k=0 gives A020330.
T(n+1,n) gives A080565(n+1).
T(2n,n) gives A246831.
Main diagonal gives A005843.
Cf. A007088, A030308, A051162, A025581, A246520 (row maxima).

Programs

  • Haskell
    import Data.Function (on)
    a246830 n k = a246830_tabl !! n !! k
    a246830_row n = a246830_tabl !! n
    a246830_tabl = zipWith (zipWith f) a051162_tabl a025581_tabl where
       f x y = foldr (\b v -> 2 * v + b) 0 $ x |+| y
       (|+|) = (++) `on` a030308_row
    -- Reinhard Zumkeller, Sep 04 2014
    
  • Maple
    f:= proc(i, j) local r, h, k; r:=0; h:=0; k:=j;
          while k>0 do r:=r+2^h*irem(k, 2, 'k'); h:=h+1 od; k:=i;
          while k>0 do r:=r+2^h*irem(k, 2, 'k'); h:=h+1 od; r
        end:
    T:= (n, k)-> f(n-k, n+k):
    seq(seq(T(n, k), k=0..n), n=0..14);
  • Mathematica
    f[i_, j_] := Module[{r, h, k, m}, r=0; h=0; k=j; While[k>0, {k, m} = QuotientRemainder[k, 2]; r = r+2^h*m; h = h+1]; k=i; While[k>0, {k, m} = QuotientRemainder[k, 2]; r = r+2^h*m; h = h+1]; r]; T[n_, k_] := f[n-k, n+k]; Table[Table[T[n, k], {k, 0, n}], {n, 0, 14}] // Flatten (* Jean-François Alcover, Oct 03 2016, adapted from Maple *)
  • Python
    A246830 = []
    for n in range(10**2):
        for k in range(n):
            A246830.append(int(bin(n-k)[2:]+bin(n+k)[2:],2))
        A246830.append(2*n) # Chai Wah Wu, Sep 05 2014

A070771 b+c+d+e where b>=c>=d>=e>=0 ordered by b then c then d then e.

Original entry on oeis.org

0, 1, 2, 3, 4, 2, 3, 4, 5, 4, 5, 6, 6, 7, 8, 3, 4, 5, 6, 5, 6, 7, 7, 8, 9, 6, 7, 8, 8, 9, 10, 9, 10, 11, 12, 4, 5, 6, 7, 6, 7, 8, 8, 9, 10, 7, 8, 9, 9, 10, 11, 10, 11, 12, 13, 8, 9, 10, 10, 11, 12, 11, 12, 13, 14, 12, 13, 14, 15, 16, 5, 6, 7, 8, 7, 8, 9, 9, 10, 11, 8, 9, 10, 10, 11, 12, 11
Offset: 0

Views

Author

Henry Bottomley, May 06 2002

Keywords

Crossrefs

Cf. A001477, A051162, A070770, A070772 for similar sequences with different numbers of terms summed.

A070772 b+c+d+e+f where b>=c>=d>=e>=f>=0 ordered by b then c then d then e then f.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 2, 3, 4, 5, 6, 4, 5, 6, 7, 6, 7, 8, 8, 9, 10, 3, 4, 5, 6, 7, 5, 6, 7, 8, 7, 8, 9, 9, 10, 11, 6, 7, 8, 9, 8, 9, 10, 10, 11, 12, 9, 10, 11, 11, 12, 13, 12, 13, 14, 15, 4, 5, 6, 7, 8, 6, 7, 8, 9, 8, 9, 10, 10, 11, 12, 7, 8, 9, 10, 9, 10, 11, 11, 12, 13, 10, 11, 12, 12, 13, 14
Offset: 0

Views

Author

Henry Bottomley, May 06 2002

Keywords

Crossrefs

Cf. A001477, A051162, A070770, A070771 for similar sequences with different numbers of terms summed.

A134478 Triangle read by rows, T(0,0) = 1; n-th row = (n+1) terms of n, n+1, n+2, ...

Original entry on oeis.org

1, 1, 2, 2, 3, 4, 3, 4, 5, 6, 4, 5, 6, 7, 8, 5, 6, 7, 8, 9, 10, 6, 7, 8, 9, 10, 11, 12, 7, 8, 9, 10, 11, 12, 13, 14, 8, 9, 10, 11, 12, 13, 14, 15, 16, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18
Offset: 0

Views

Author

Gary W. Adamson, Oct 27 2007

Keywords

Comments

Apart from the irregular choice of T(0,0) the same as A051162. - R. J. Mathar, Mar 28 2012

Examples

			First few rows of the triangle:
  1;
  1, 2;
  2, 3, 4;
  3, 4, 5,  6;
  4, 5, 6,  7,  8;
  5, 6, 7,  8,  9, 10;
  6, 7, 8,  9, 10, 11, 12;
  7, 8, 9, 10, 11, 12, 13, 14;
  ...
		

Crossrefs

Cf. A051162, A134479 (row sums), A126804 (row products).

Programs

  • Mathematica
    Join[{1},Flatten[Table[Range[n,2n],{n,10}]]] (* Harvey P. Dale, Nov 21 2014 *)
  • PARI
    concat([1], for(n=1,10, for(k=0,n, print1(n+k, ", ")))) \\ G. C. Greubel, Sep 24 2017

A328901 Triangle T(n, k) read by rows: T(n, k) is the numerator of the rational Catalan number defined as binomial(n + k, n)/(n + k) for n > 0 and T(0, 0) = 1.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 1, 1, 2, 10, 1, 1, 5, 5, 35, 1, 1, 3, 7, 14, 126, 1, 1, 7, 28, 21, 42, 77, 1, 1, 4, 12, 30, 66, 132, 1716, 1, 1, 9, 15, 165, 99, 429, 429, 6435, 1, 1, 5, 55, 55, 143, 1001, 715, 1430, 24310, 1, 1, 11, 22, 143, 1001, 1001, 1144, 2431, 4862, 46189, 1, 1, 6, 26, 91, 273, 728, 1768, 3978, 8398, 16796, 352716
Offset: 0

Views

Author

Stefano Spezia, Oct 30 2019

Keywords

Examples

			n\k|   0   1   2   3   4   5   6
---+----------------------------
0  |   1
1  |   1   1
2  |   1   1   3
3  |   1   1   2  10
4  |   1   1   5   5  35
5  |   1   1   3   7  14 126
6  |   1   1   7  28  21  42  77
...
		

Crossrefs

Main diagonal gives A201058 (for n>0).
Cf. A000108, A046899, A051162, A328902 (denominator).

Programs

  • Mathematica
    Flatten[Join[{1},Table[LCM[Binomial[n+k,n],n+k]/(n+k),{n,1,11},{k,0,n}]]]

Formula

T(n, k) = lcm(binomial(n + k, n), n + k)/(n + k) for n > 0.

A328902 Triangle T(n, k) read by rows: T(n, k) is the denominator of the rational Catalan number defined as binomial(n + k, n)/(n + k) for 0 <= k <= n, n > 0; T(0, 0) = 1.

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 3, 1, 1, 3, 4, 1, 2, 1, 4, 5, 1, 1, 1, 1, 5, 6, 1, 2, 3, 1, 1, 1, 7, 1, 1, 1, 1, 1, 1, 7, 8, 1, 2, 1, 4, 1, 2, 1, 8, 9, 1, 1, 3, 1, 1, 3, 1, 1, 9, 10, 1, 2, 1, 2, 5, 2, 1, 1, 1, 5, 11, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 11, 12, 1, 2, 3, 4, 1, 3, 1, 2, 3, 1, 1, 6
Offset: 0

Views

Author

Stefano Spezia, Oct 30 2019

Keywords

Examples

			n\k| 0 1 2 3 4 5 6
---+--------------
0  | 1
1  | 1 1
2  | 2 1 2
3  | 3 1 1 3
4  | 4 1 2 1 4
5  | 5 1 1 1 1 5
6  | 6 1 2 3 1 1 1
...
		

Crossrefs

Cf. A000108, A028310 (1st column), A046899, A051162, A328901 (numerator).

Programs

  • Mathematica
    Flatten[Join[{1},Table[(n+k)/GCD[n+k,Binomial[n+k,n]],{n,1,12},{k,0,n}]]]
  • PARI
    A328902(n,k)=if(n,(n+k)/gcd(binomial(n+k,n),n+k),1) \\ M. F. Hasler, Nov 04 2019

Formula

T(n, k) = (n + k)/gcd(binomial(n + k, n), n + k) for n > 0.

A100937 Main diagonal of symmetric square array A100936.

Original entry on oeis.org

1, 3, 14, 76, 435, 2577, 15678, 97272, 612126, 3891890, 24933292, 160663328, 1040074684, 6759228932, 44075916696, 288289595968, 1890894150707, 12434303045721, 81960791460442, 541428229233012, 3583843659376257
Offset: 0

Views

Author

Paul D. Hanna, Nov 23 2004

Keywords

Examples

			a(3) = 76 = 1*1 + 3^2*2 + 3^2*5 + 1*12 = Sum_{k=0..3} C(3,k)^2*A051163(k).
a(4) = 435 = 1*1 + 4^2*2 + 6^2*5 + 4^2*12 + 1*30 = Sum_{k=0..4} C(4,k)^2*A051163(k).
		

Crossrefs

Programs

  • PARI
    
    				

Formula

a(n) = Sum_{k=0..n} C(n, k)^2*A051162(k).

A105125 Triangle read by rows: T(n,k) = n^3 + k^3, n >= 0, 0 <= k <= n.

Original entry on oeis.org

0, 1, 2, 8, 9, 16, 27, 28, 35, 54, 64, 65, 72, 91, 128, 125, 126, 133, 152, 189, 250, 216, 217, 224, 243, 280, 341, 432, 343, 344, 351, 370, 407, 468, 559, 686, 512, 513, 520, 539, 576, 637, 728, 855, 1024, 729, 730, 737, 756, 793, 854, 945, 1072, 1241, 1458, 1000, 1001, 1008, 1027
Offset: 0

Views

Author

Roger L. Bagula, Apr 09 2005

Keywords

Examples

			Triangle begins (modulo 2 plot is a checkerboard):
  {0}
  {1, 2}
  {8, 9, 16}
  {27, 28, 35, 54}
  {64, 65, 72, 91, 128}
  {125, 126, 133, 152, 189, 250}
  ...
The identity for T(2, 1): 9 = 3*(3^2 + 3*1^2)/4 = 3*12/4 = 9. - _Wolfdieter Lang_, May 15 2015
		

Crossrefs

Cf. A069011. Different from A004999. A257238, A025581, A051162.

Programs

  • Maple
    seq(seq(n^3+k^3,k=0..n),n=0..10); # Robert Israel, May 15 2015
  • Mathematica
    f[n_, m_, p_] := n^p + m^p p = 3 a = Table[Table[f[n, m, p], {n, 0, m}], {m, 0, 20}] aa = Flatten[a]

Formula

T(n,k) = n^3 + k^3, n >= 0, 0 <= k <= n.
T(n, k) = A051162(n, k)*(A051162(n, k)^2 + 3* A025581(n, k)^2)/4. See the comment on A051162 for this identity. - Wolfdieter Lang, May 15 2015
G.f. for triangle: -(9*x^5*y^3 - 8*x^4*y^3 - x^4*y^2 + 7*x^3*y^3 - 36*x^3*y^2 - 2*x^2*y^3 + 5*x^3*y + 27*x^2*y^2 + 12*x^2*y - 8*x*y^2 - x^2 + 3*x*y - 4*x - 2*y - 1)*x/((x-1)^4*(x*y-1)^4). - Robert Israel, May 15 2015

A368045 Triangle read by rows. T(n, k) = (k*(k + 1)*(2*k + 1) + n*(n + 1)*(2*n + 1)) / 6.

Original entry on oeis.org

0, 1, 2, 5, 6, 10, 14, 15, 19, 28, 30, 31, 35, 44, 60, 55, 56, 60, 69, 85, 110, 91, 92, 96, 105, 121, 146, 182, 140, 141, 145, 154, 170, 195, 231, 280, 204, 205, 209, 218, 234, 259, 295, 344, 408, 285, 286, 290, 299, 315, 340, 376, 425, 489, 570
Offset: 0

Views

Author

Peter Luschny, Dec 09 2023

Keywords

Comments

Consider a sequence-to-triangle transformation a -> T, where a is a 0-based sequence and T a regular (0, 0)-based triangular array. The transformation is recursively defined, starting with T(0, 0) = 0, and T(n, n) = a(n) + T(n, n - 1) for n > 0. For k <> n let T(n, k) = a(n) + T(n-1, k).
If a(n) = 1, then T = A051162; if a(n) = n, then T = A367964 (generalizing the triangular numbers); if a(n) = n^2, then T is this triangle.
In the multiplicative form of the transformation, T(0, 0) is set to 1, and the operation '+' is replaced by '*'. For instance, a(n) = 2 is then mapped to T = A368043 and a(n) = n to A143216.

Examples

			Triangle T(n, k) starts:
  [0] [  0]
  [1] [  1,   2]
  [2] [  5,   6,  10]
  [3] [ 14,  15,  19,  28]
  [4] [ 30,  31,  35,  44,  60]
  [5] [ 55,  56,  60,  69,  85, 110]
  [6] [ 91,  92,  96, 105, 121, 146, 182]
  [7] [140, 141, 145, 154, 170, 195, 231, 280]
  [8] [204, 205, 209, 218, 234, 259, 295, 344, 408]
  [9] [285, 286, 290, 299, 315, 340, 376, 425, 489, 570]
		

Crossrefs

Cf. A000330 (T(n,0)), A056520 (T(n,1)), A005900 (T(n-1,n)), A006331 (T(n,n)), A094952 (T(2*n,n)), A368046 (row sums), A368047 (alternating row sums).
Cf. A051162 (transform of n^0), A367964 (transform of n^1), this sequence (transform of n^2).

Programs

  • Mathematica
    Module[{n=1},NestList[Append[#+n^2,Last[#]+2(n++^2)]&,{0},10]] (* or *)
    Table[(k(k+1)(2k+1)+n(n+1)(2n+1))/6,{n,0,10},{k,0,n}] (* Paolo Xausa, Dec 10 2023 *)
  • Python
    from functools import cache
    @cache
    def Trow(n: int) -> list[int]:
        if n == 0: return [0]
        row = Trow(n - 1) + [0]
        for k in range(n): row[k] += n * n
        row[n] = row[n - 1] + n * n
        return row
    print([k for n in range(10) for k in Trow(n)])

Formula

T(n, k) = A000330(k) + A000330(n).

A059864 a(n) = Product_{i=4..n} (prime(i)-5), where prime(i) is i-th prime.

Original entry on oeis.org

1, 1, 1, 2, 12, 96, 1152, 16128, 290304, 6967296, 181149696, 5796790272, 208684449792, 7930009092096, 333060381868032, 15986898329665536, 863292509801938944, 48344380548908580864, 2997351594032332013568
Offset: 1

Views

Author

Labos Elemer, Feb 28 2001

Keywords

Comments

Such products arise in Hardy-Littlewood prime k-tuplet conjectural formulas.

References

  • Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 84-94.
  • R. K. Guy, Unsolved Problems in Number Theory, A8, A1
  • G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers, 5th ed., Oxford Univ. Press, 1979.
  • G. Polya, Mathematics and Plausible Reasoning, Vol. II, Appendix Princeton UP, 1954

Crossrefs

Programs

  • Magma
    [n le 3 select 1 else (&*[NthPrime(j) -5: j in [4..n]]): n in [1..30]]; // G. C. Greubel, Feb 02 2023
    
  • Mathematica
    Join[{1,1,1},FoldList[Times,Prime[Range[4,20]]-5]] (* Harvey P. Dale, Dec 29 2018 *)
  • PARI
    a(n) = prod(k=4, n, prime(k)-5); \\ Michel Marcus, Dec 12 2017
    
  • SageMath
    def A059864(n): return product(nth_prime(j) -5 for j in range(4,n+1))
    [A059864(n) for n in range(1,31)] # G. C. Greubel, Feb 02 2023
Previous Showing 11-20 of 25 results. Next