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.

A321124 a(n) = (4*n^3 - 6*n^2 + 14*n + 3)/3.

Original entry on oeis.org

1, 5, 13, 33, 73, 141, 245, 393, 593, 853, 1181, 1585, 2073, 2653, 3333, 4121, 5025, 6053, 7213, 8513, 9961, 11565, 13333, 15273, 17393, 19701, 22205, 24913, 27833, 30973, 34341, 37945, 41793, 45893, 50253, 54881, 59785, 64973, 70453, 76233, 82321, 88725
Offset: 0

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Author

Keywords

Comments

For n >= 5, a(n) is the number of evaluation points on the n-dimensional cube in Phillips-Dobrodeev's degree 7 cubature rule.

Crossrefs

Programs

  • Mathematica
    Table[(4*n^3 - 6*n^2 + 14*n + 3)/3, {n, 0, 50}]
  • Maxima
    makelist((4*n^3 - 6*n^2 + 14*n + 3)/3, n, 0, 50);

Formula

a(n) = 8*binomial(n, 3) + 4*binomial(n, 2) + 4*binomial(n, 1) + 1.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4), n >= 4.
a(n) = a(n-1) + A128445(n+1), n >= 1.
E.g.f.: (1/3)*(3 + 12*x + 6*x^2 + 4*x^3)*exp(x).
G.f.: (1 + x - x^2 + 7*x^3)/(1 - x)^4.

A162024 Number of n X n binary arrays with rows and columns, considered as binary numbers, in nondecreasing order, and all but the outermost row or column zero.

Original entry on oeis.org

7, 20, 40, 68, 104, 148, 200, 260, 328, 404, 488, 580, 680, 788, 904, 1028, 1160, 1300, 1448, 1604, 1768, 1940, 2120, 2308, 2504, 2708, 2920, 3140, 3368, 3604, 3848, 4100, 4360, 4628, 4904, 5188, 5480, 5780, 6088, 6404, 6728, 7060, 7400, 7748, 8104, 8468
Offset: 2

Views

Author

R. H. Hardin, Jun 25 2009

Keywords

Formula

Empirical: a(n)= 3*a(n-1) - 3*a(n-2) + a(n-3), n>5. a(n)= A128445(n+1), n>2. - R. J. Mathar, Aug 11 2009
Conjectures from Colin Barker, Mar 24 2018: (Start)
G.f.: x^2*(7 - x + x^2 + x^3) / (1 - x)^3.
a(n) = 4*(2 - 2*n + n^2) for n>2.
(End)

A155901 Arise in p-adic valuations of sequences counting alternating sign matrices.

Original entry on oeis.org

2, 8, 5, 12, 5, 14, 8, 14
Offset: 1

Views

Author

Jonathan Vos Post, Jan 30 2009

Keywords

Comments

These are the values from Table 1 p.14 of Sun and Moll.

Examples

			a(7) = 8 because "the eight solutions to Nu(T(n)) = 7 are 26, 38, 46, 82, 5462, 10922, 10924 and J_15 - 1 = 21844" where J_k = k-th Jacobsthal number = A001045(k).
		

References

  • D. Bressoud, Proofs and Confirmations: the story of the Alternating Sign Matrix Conjecture, Cambridge University Press, 1999.

Crossrefs

Showing 1-3 of 3 results.