A283026 Number of inequivalent 4 X 4 matrices with entries in {1,2,3,..,n} up to row permutations.

0, 1, 3876, 1929501, 183181376, 6419043125, 118091211876, 1388168405001, 11745311589376, 77279801651001, 416916712502500, 1915356782994501, 7705740009485376, 27731516944463501, 90762229896563876, 273716119247180625, 768684707117285376, 2027695320242670001

Offset: 0

Author

David Nacin, Feb 27 2017

Keywords

• easy
• nonn

Comments

Cycle index of symmetry group S4 acting on the 16 entries is (6*s(2)^4s(1)^8 + 8*s(3)^4s(1)^4 + 3*s(2)^8 + 6*s(4)^4 + s(1)^{16})/24.

Examples

			For n=2 we get a(2)=3876 inequivalent 4x4 binary matrices up to row permutations.
		

Crossrefs

Cf. A282613, A282614, A283027, A283028, A283029, A283031, A283032, A283033. A283030 (5x5 version). A282612 (3x3 version). A037270 (2x2 version).

Programs

Mathematica

Table[n^4*(n^4 + 1)*(n^4 + 2)*(n^4 + 3)/24,{n,0,30}]

PARI

a(n) = n^4*(n^4 + 1)*(n^4 + 2)*(n^4 + 3)/24; \\ Indranil Ghosh, Feb 27 2017

Python

def A283026(n) : return n**4*(n**4 + 1)*(n**4 + 2)*(n**4 + 3)/24 # Indranil Ghosh, Feb 27 2017

Formula

a(n) = n^4*(n^4 + 1)*(n^4 + 2)*(n^4 + 3)/24.

From Chai Wah Wu, Dec 07 2018: (Start)

a(n) = 17*a(n-1) - 136*a(n-2) + 680*a(n-3) - 2380*a(n-4) + 6188*a(n-5) - 12376*a(n-6) + 19448*a(n-7) - 24310*a(n-8) + 24310*a(n-9) - 19448*a(n-10) + 12376*a(n-11) - 6188*a(n-12) + 2380*a(n-13) - 680*a(n-14) + 136*a(n-15) - 17*a(n-16) + a(n-17) for n > 16.

G.f.: -x*(x + 1)*(x^14 + 3858*x^13 + 1859887*x^12 + 149046428*x^11 + 3415692141*x^10 + 29161611758*x^9 + 104450960739*x^8 + 161533106376*x^7 + 104450960739*x^6 + 29161611758*x^5 + 3415692141*x^4 + 149046428*x^3 + 1859887*x^2 + 3858*x + 1)/(x - 1)^17. (End)