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.

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A236538 Triangle read by rows: T(n,k) = (n+1)*2^(n-2)+(k-1)*2^(n-1) for 1 <= k <= n.

Original entry on oeis.org

1, 3, 5, 8, 12, 16, 20, 28, 36, 44, 48, 64, 80, 96, 112, 112, 144, 176, 208, 240, 272, 256, 320, 384, 448, 512, 576, 640, 576, 704, 832, 960, 1088, 1216, 1344, 1472, 1280, 1536, 1792, 2048, 2304, 2560, 2816, 3072, 3328, 2816, 3328, 3840, 4352, 4864, 5376
Offset: 1

Views

Author

Fedor Igumnov, Jan 28 2014

Keywords

Comments

1, 9, 45, 161, 497, 1409, ... is the sequence of perimeters (sum of border elements) of the triangle.
1, 5, 80, 3520, 394240, 107233280, 68629299200, ... is the sequence of determinants of the triangle.
Only the first three terms are odd.

Examples

			Triangle begins:
================================================
\k |    1     2     3     4     5     6     7
n\ |
================================================
1  |    1;
2  |    3,    5;
3  |    8,   12,   16;
4  |   20,   28,   36,   44;
5  |   48,   64,   80,   96,  112;
6  |  112,  144,  176,  208,  240,  272;
7  |  256,  320,  384,  448,  512,  576,  640;
...
		

Crossrefs

Cf. A001792 (column 1), A053220 (right border). Also:
A014477, row sums;
A036826, partial sums;
A058962, central elements in odd rows;
A045623, second column;
A045891, third column;
A034007, fourth column;
A167667, subdiagonal;
A130129, second subdiagonal.

Programs

  • C
    int a(int n, int k) {return (n+1)*pow(2,n-2)+(k-1)*pow(2,n-1);}
    
  • Magma
    /* As triangle: */ [[(n+1)*2^(n-2)+(k-1)*2^(n-1): k in [1..n]]: n in [1..10]]; // Bruno Berselli, Jan 28 2014
  • Mathematica
    t[n_, k_] := (n + 1)*2^(n - 2) + (k - 1)*2^(n - 1); Table[t[n, k], {n, 10}, {k, n}] // Flatten (* Bruno Berselli, Jan 28 2014 *)

Formula

T(n,k) = T(n-1,k) + T(n-1,k+1).
Sum_{k=1..n} T(n,k) = n^2*2^(n-1) = A014477(n-1).

Extensions

More terms from Bruno Berselli, Jan 28 2014

A372493 G.f. A(x) satisfies A(A(x)) = Sum_{k>=1} k^2 * 2^(k-1) * x^k.

Original entry on oeis.org

0, 1, 4, 2, 12, -30, 24, 1412, -18716, 127750, -19448, -10721556, 98983992, 546122580, -19718580272, 30721006440, 4638904011364, -44204880124922, -1218793973236472, 26364933421291468, 327900715232299304, -15425392878552410820, -62258050574118828336
Offset: 0

Views

Author

Seiichi Manyama, May 03 2024

Keywords

Crossrefs

A095677 Triangle T(n,k), 0<=k<=n, read by rows, defined by Sum_{k = 0..n} T(n,k)*x^k = Sum_{k = 0..n} binomial(n,k)*(x+k)^n.

Original entry on oeis.org

1, 1, 2, 6, 8, 4, 54, 72, 36, 8, 680, 896, 480, 128, 16, 11000, 14400, 8000, 2400, 400, 32, 217392, 283392, 161280, 51840, 10080, 1152, 64, 5076400, 6598144, 3819648, 1285760, 274400, 37632, 3136, 128, 136761984, 177373184, 103993344
Offset: 0

Views

Author

Philippe Deléham Jul 04 2004

Keywords

Examples

			1; 1, 2; 6, 8, 4; 54, 72, 36, 8; 680, 896, 480, 128, 16; ...
		

Formula

T(n, k) = binomial(n, k)*Sum_{j = 0..n} = binomial(n, j)*j^(n-k).
T(n, n) = 2^n, see A000079.
T(n+1, n) = (n+1)^2*2^n, see A014477.
T(n, 0) = n*Sum_{k = 0..n-1} T(n-1, k).

A176676 Primes not of the form prime + k^2*2^(k-1).

Original entry on oeis.org

2, 5, 7, 17, 23, 29, 71, 101, 113, 127, 179, 191, 197, 223, 239, 251, 257, 281, 283, 311, 331, 337, 359, 401, 449, 463, 491, 521, 541, 569, 587, 617, 647, 659, 673, 701, 733, 739, 743, 757, 761, 827, 853, 877, 881, 883, 907, 911, 929, 953, 997, 1051, 1063, 1093
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Apr 23 2010

Keywords

Crossrefs

Cf. A014477.

Programs

  • Maple
    From R. J. Mathar, Apr 27 2010: (Start)
    A014477 := proc(n) (n+1)^2*2^n ; end proc:
    isA176676 := proc(p) local n,a77 ; if not isprime(p) then return false; end if; for n from 1 do a77 := A014477(n-1) ; if isprime(p-a77) then return false; elif p-a77<2 then return true; end if; end do: end proc:
    for n from 1 to 300 do p := ithprime(n) ; if isA176676(p) then printf("%d,",p) ; end if; end do: (End)

Extensions

Corrected (149 replaced by 179, 269 removed, 643 removed, 743 and 911 and 1053 inserted) by R. J. Mathar, Apr 27 2010
Previous Showing 11-14 of 14 results.