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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A322268 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f. exp(x)*(sec(x) + tan(x))^k.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 4, 1, 1, 4, 9, 9, 1, 1, 5, 16, 29, 24, 1, 1, 6, 25, 67, 105, 77, 1, 1, 7, 36, 129, 304, 433, 294, 1, 1, 8, 49, 221, 705, 1519, 2029, 1309, 1, 1, 9, 64, 349, 1416, 4145, 8386, 10709, 6664, 1, 1, 10, 81, 519, 2569, 9601, 26385, 51007, 63025, 38177, 1, 1, 11, 100, 737, 4320, 19777, 69406, 181969, 340024, 409713, 243034, 1
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 01 2018

Keywords

Examples

			E.g.f. of column k: A_k(x) = 1 + (k + 1)*x/1! + (k + 1)^2*x^2/2! + (k^3 + 3*k^2 + 4*k + 1)*x^3/3! + (k^4 + 4*k^3 + 10*k^2 + 8*k + 1)*x^4/4! + ...
Square array begins:
  1,   1,    1,     1,     1,     1,  ...
  1,   2,    3,     4,     5,     6,  ...
  1,   4,    9,    16,    25,    36,  ...
  1,   9,   29,    67,   129,   221,  ...
  1,  24,  105,   304,   705,  1416,  ...
  1,  77,  433,  1519,  4145,  9601,  ...
		

Crossrefs

Columns k=0..3 give A000012, A000667, A292756, A292759.
Main diagonal gives A296793.
Cf. A322267.

Programs

  • Mathematica
    Table[Function[k, n! SeriesCoefficient[Exp[x] (Sec[x] + Tan[x])^k, {x, 0, n}]][j - n], {j, 0, 11}, {n, 0, j}] // Flatten

Formula

E.g.f. of column k: exp(x)*(sec(x) + tan(x))^k.

A298244 a(n) = n! * [x^n] (sec(x) + tan(x))^n.

Original entry on oeis.org

1, 1, 4, 30, 320, 4400, 74016, 1472240, 33800192, 879646464, 25589632000, 822867814912, 28982612385792, 1109640105852928, 45884917741981696, 2038015221365667840, 96765606087737999360, 4890992991269273403392, 262201755871367895711744, 14859866059895961631981568, 887693530413229611155456000
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 15 2018

Keywords

Crossrefs

Main diagonal of A322267.

Programs

  • Mathematica
    Table[n! SeriesCoefficient[(Sec[x] + Tan[x])^n, {x, 0, n}], {n, 0, 20}]

Formula

a(n) ~ n! * c * d^n / sqrt(n), where d = 3.063838405249746742835218125232... and c = 0.308377491585051819518915209... - Vaclav Kotesovec, Aug 17 2019
Showing 1-2 of 2 results.