A037270 -id:A037270 - cp's OEIS frontend

A173130 a(n) = Cosh[(2 n - 1) ArcCosh[n]].

0, 1, 26, 3363, 937444, 456335045, 343904160606, 371198523608647, 543466014742175624, 1036834190110356583689, 2499384905955651114739810, 7429238104512325157021090411, 26695718139185294187938997247212

Offset: 0

Artur Jasinski, Feb 10 2010

nonn

Cf. A058331, A001079, A037270, A071253, A108741, A132592, A146311, A146312, A146313, A173115, A173116, A173121, A173127, A173128.

Table[Round[Cosh[(2 n - 1) ArcCosh[n]]], {n, 0, 20}] (* Artur Jasinski *)

a(n) ~ 2^(2*n-2) * n^(2*n-1). - Vaclav Kotesovec, Apr 05 2016

A173131 a(n) = (Cosh[(2n-1)ArcSinh[n]])^2.

Original entry on oeis.org

1, 2, 1445, 19740250, 1361599599377, 298514762397852026, 160545187370375075046277, 179656719395983409634002348450, 373368546362937441101158606899394625

Offset: 0

Artur Jasinski, Feb 10 2010

nonn

Cf. A058331, A001079, A037270, A071253, A108741, A132592, A146311, A146312, A146313, A173115, A173116, A173121, A173127, A173128, A173129, A173130.

Table[Round[Cosh[(2 n - 1) ArcSinh[n]]^2], {n, 0, 10}] (* Artur Jasinski *)

a(n) ~ 2^(4*n-4) * n^(4*n-2). - Vaclav Kotesovec, Apr 05 2016

A173133 a(n) = Sinh[(2n-1) ArcSinh[n]].

Original entry on oeis.org

0, 1, 38, 4443, 1166876, 546365045, 400680904674, 423859315570607, 611038907405197432, 1151555487914640463209, 2748476184146759127540190, 8102732939160371170806346243, 28915133156938367486730067779348

Offset: 0

Artur Jasinski, Feb 10 2010

nonn

Cf. A058331, A001079, A037270, A071253, A108741, A132592, A146311, A146312, A146313, A173115, A173116, A173121, A173127, A173128, A173129, A173130, A173131.

Table[Round[Sinh[(2 n - 1) ArcSinh[n]]], {n, 0, 20}] (* Artur Jasinski *)
Round[Table[1/2 (n - Sqrt[1 + n^2])^(2 n - 1) + 1/2 (n + Sqrt[1 + n^2])^(2 n - 1), {n, 0, 10}]] (* Artur Jasinski, Feb 14 2010 *)

a(n) = 1/2 (n - sqrt(1 + n^2))^(2 n - 1) + 1/2 (n + sqrt(1 + n^2))^(2 n - 1). - Artur Jasinski, Feb 14 2010

Minor edits by Vaclav Kotesovec, Apr 05 2016

A241016 Triangle read by rows: T(n, k) = sum of k-th row of n X n square filled with the numbers 1 through n^2 reading across rows left-to-right.

Original entry on oeis.org

1, 3, 7, 6, 15, 24, 10, 26, 42, 58, 15, 40, 65, 90, 115, 21, 57, 93, 129, 165, 201, 28, 77, 126, 175, 224, 273, 322, 36, 100, 164, 228, 292, 356, 420, 484, 45, 126, 207, 288, 369, 450, 531, 612, 693, 55, 155, 255, 355, 455, 555, 655, 755, 855, 955, 66, 187, 308, 429, 550

Offset: 1

Kival Ngaokrajang, Aug 08 2014

See illustration in links.

The corresponding triangle with column sums is found in A251630. - Wolfdieter Lang, Dec 09 2014

			The triangle T(n, k) begins:
n\k  1   2   3   4   5   6   7   8   9  10 ...
1:   1
2:   3   7
3:   6  15  24
4:  10  26  42  58
5:  15  40  65  90 115
6:  21  57  93 129 165 201
7:  28  77 126 175 224 273 322
8:  36 100 164 228 292 356 420 484
9:  45 126 207 288 369 450 531 612 693
10: 55 155 255 355 455 555 655 755 855 955
... reformatted - _Wolfdieter Lang_, Dec 08 2014

G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened
Kival Ngaokrajang, Illustration of initial terms

Columns k=1..6: A000217, A005449, A005475, A022265, A022267, A022269.
Diagonals: A081436, A059270, ...
Row sums: A037270.

Table[Sum[n*(k - 1) + j, {j,1,n}], {n,1,10}, {k,1,n}] // Flatten (* G. C. Greubel, Aug 23 2017 *)

trg(nn) = {for (n=1, nn, mm = matrix(n, n, i, j, j + n*(i-1)); for (i=1, n, print1(sum(j=1, n, mm[i, j]), ", ");); print(););} \\ Michel Marcus, Sep 15 2014

T(n, k) = Sum_{j=1..n} (n*(k-1)+ j), for n >= k >= 1. See the Michel Marcus program. - Wolfdieter Lang, Dec 08 2014

T(n, k) = binomial(n+1, 2) + n^2*(k-1). - Wolfdieter Lang, Dec 09 2014

Edited. - Wolfdieter Lang, Dec 08 2014

A283030 Number of inequivalent 5 X 5 matrices with entries in {1,2,3,...,n} up to row permutations.

Original entry on oeis.org

0, 1, 376992, 7355513529, 9474438804480, 2491483056641250, 237223883948569056, 11182222570880983622, 314920519245916176384, 5983496429606726016735, 83341666958337500020000, 902948225666983587054711, 7950004204832195461143552, 58805000552467321853765064

Offset: 0

David Nacin, Feb 27 2017

Cycle index of symmetric group S4 on the set of 25 entries is (10*s(2)^5*s(1)^15 + 20*s(3)^5*s(1)^10 + 15*s(2)^10*s(1)^5 + 30*s(4)^5*s(1)^5 + 20*s(2)^5*s(3)^5 + 24*s(5)^5+s(1)^25)/120.

			For n=2 we get a(2)=376992 inequivalent 5 X 5 binary matrices up to row permutations.

G. C. Greubel, Table of n, a(n) for n = 0..1000

Cf. A282613, A282614, A283027, A283028, A283029, A283031, A283032, A283033.

Cf. A283026 (4 X 4 version), A282612 (3 X 3 version), A037270 (2 X 2 version).

List([0..20], n -> n^5*(n^20 +10*n^15 +35*n^10 +50*n^5 +24)/120); # G. C. Greubel, Dec 07 2018

[n^5*(n^20 +10*n^15 +35*n^10 +50*n^5 +24)/120: n in [0..20]]; // G. C. Greubel, Dec 07 2018

[(10*n^20+35*n^15+50*n^10+24*n^5+n^25)/120$n=0..16]; # Muniru A Asiru, Dec 07 2018

Table[(10n^20+ 35n^15 + 50n^10 + 24n^5 + n^25)/120, {n, 0, 16}]

a(n) = (10*n^20 + 35*n^15 + 50*n^10 + 24*n^5 + n^25)/120; \\ Indranil Ghosh, Feb 27 2017

def A283030(n): return (10*n**20 + 35*n**15 + 50*n**10 + 24*n**5 + n**25)/120 # Indranil Ghosh, Feb 27 2017

[n^5*(n^20 +10*n^15 +35*n^10 +50*n^5 +24)/120 for n in range(20)] # G. C. Greubel, Dec 07 2018

a(n) = (n^25 + 10*n^20 + 35*n^15 + 50*n^10 + 24*n^5)/120.
From Chai Wah Wu, Dec 07 2018: (Start)
a(n) = 26*a(n-1) - 325*a(n-2) + 2600*a(n-3) - 14950*a(n-4) + 65780*a(n-5) - 230230*a(n-6) + 657800*a(n-7) - 1562275*a(n-8) + 3124550*a(n-9) - 5311735*a(n-10) + 7726160*a(n-11) - 9657700*a(n-12) + 10400600*a(n-13) - 9657700*a(n-14) + 7726160*a(n-15) - 5311735*a(n-16) + 3124550*a(n-17) - 1562275*a(n-18) + 657800*a(n-19) - 230230*a(n-20) + 65780*a(n-21) - 14950*a(n-22) + 2600*a(n-23) - 325*a(n-24) + 26*a(n-25) - a(n-26) for n > 25.
G.f.: x*(201376*x^23 + 6769097812*x^22 + 9115118766616*x^21 + 2236218775591321*x^20 + 175251248958400030*x^19 + 5797456665826176046*x^18 + 94937993285056078902*x^17 + 849635569433212953261*x^16 + 4430970723887327210136*x^15 + 14044903652456409705760*x^14 + 27788396155245137222056*x^13 + 34830392581327241688322*x^12 + 27788479931754180338596*x^11 + 14044908029988217540516*x^10 + 4430933630938187561140*x^9 + 849629302807069561746*x^8 + 94943797840269544152*x^7 + 5799609980863901436*x^6 + 175505398388141776*x^5 + 2247537209457445*x^4 + 9283317972526*x^3 + 7345712062*x^2 + 376966*x + 1)/(x - 1)^26. (End)

A331351 Number of achiral colorings of the edges of a cube or regular octahedron.

Original entry on oeis.org

1, 70, 1407, 12480, 69050, 281946, 931490, 2632512, 6598935, 15041950, 31740841, 62830560, 117855192, 211141490, 363551700, 604679936, 975561405, 1531968822, 2348375395, 3522668800, 5181705606, 7487800650, 10646250902

Offset: 1

Robert A. Russell, Jan 14 2020

A cube has 8 vertices and 12 edges. A regular octahedron has 6 vertices and 12 edges. An achiral coloring is identical to its reflection.
From Robert A. Russell, Oct 08 2020: (Start)
The Schläfli symbols for the cube and regular octahedron are {4,3} and {3,4} respectively. They are mutually dual.
There are 24 elements in the automorphism group of the regular octahedron/cube that are not in the rotation group. They divide into five conjugacy classes. The first formula is obtained by averaging the edge cycle indices after replacing x_i^j with n^j according to the Pólya enumeration theorem.
  Conjugacy Class     Count    Odd Cycle Indices
  Inversion              1     x_2^6
  Vertex rotation*       8     x_6^2            Asterisk indicates that the
  Edge rotation*         6     x_1^2x_2^5       operation is followed by an
  Small face rotation*   3     x_4^3            inversion.
  Large face rotation*   6     x_1^4x_2^4 (End)

G. Royle, Partitions and Permutations
Index entries for linear recurrences with constant coefficients, signature (9, -36, 84, -126, 126, -84, 36, -9, 1).

Cf. A060530 (oriented), A199406 (unoriented), A337406 (chiral), A337897 (octahedron faces, cube vertices), A337898 (cube faces, octahedron vertices), A037270 (tetrahedron), A337953 (dodecahedron, icosahedron).

Row 3 of A337410 (orthotope edges, orthoplex ridges) and A337414 (orthoplex edges, orthotope ridges).

Table[(8n^2 + 6n^3 + n^6 + 6n^7 + 3n^8)/24, {n, 1, 30}]
LinearRecurrence[{9, -36, 84, -126, 126, -84, 36, -9, 1}, {1, 70, 1407, 12480, 69050, 281946, 931490, 2632512, 6598935}, 25]

a(n) = (8*n^2 + 6*n^3 + n^6 + 6*n^7 + 3*n^8) / 24.
a(n) = 1*C(n,1) + 68*C(n,2) + 1200*C(n,3) + 7268*C(n,4) + 20025*C(n,5) + 27750*C(n,6) + 18900*C(n,7) + 5040*C(n,8), where the coefficient of C(n,k) is the number of colorings using exactly k colors.
a(n) = 2*A199406(n) - A060530(n) = A060530(n) - 2*A337406(n) = A199406(n) - A337406(n). - Robert A. Russell, Oct 08 2020
G.f.: (x + 61*x^2 + 813*x^3 + 2253*x^4 + 1628*x^5 + 282*x^6 + 2*x^7) / (1-x)^9.
E.g.f.: (1/24)*exp(x)*x*(24 + 816*x + 4800*x^2 + 7268*x^3 + 4005*x^4 + 925*x^5 + 90*x^6 + 3*x^7). - Stefano Spezia, Jan 17 2020

A173134 a(n) = Sinh[(2n-1)ArcCosh[n]]^2.

Original entry on oeis.org

-1, 0, 675, 11309768, 878801253135, 208241673295152024, 118270071682117442287235, 137788343929239264227213170608, 295355309179742652677310128859789375

Offset: 0

Artur Jasinski, Feb 10 2010

sign

Cf. A058331, A001079, A037270, A071253, A108741, A132592, A146311, A146312, A146313, A173115, A173116, A173121, A173127, A173128, A173129, A173130, A173131, A173133.

Table[Round[Sinh[(2 n - 1) ArcCosh[n]]^2], {n, 0, 20}]

a(n) ~ 2^(4*n-4) * n^(4*n-2). - Vaclav Kotesovec, Apr 05 2016

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

Original entry on oeis.org

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

Offset: 0

David Nacin, Feb 27 2017

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.

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

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

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

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

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

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)

A317617 Triangle T read by rows: T(n, k) = (n^3 + n)/2 + (k - (n + 1)/2)*(n mod 2).

Original entry on oeis.org

1, 5, 5, 14, 15, 16, 34, 34, 34, 34, 63, 64, 65, 66, 67, 111, 111, 111, 111, 111, 111, 172, 173, 174, 175, 176, 177, 178, 260, 260, 260, 260, 260, 260, 260, 260, 365, 366, 367, 368, 369, 370, 371, 372, 373, 505, 505, 505, 505, 505, 505, 505, 505, 505, 505, 666

Offset: 1

Stefano Spezia, Aug 01 2018

T(n, k) is the sum of the terms of the k-th column of an n X n square matrix M formed by writing the numbers 1, ..., n^2 successively forward and backward along the rows in zig-zag pattern (proved). The n X n square matrix M is defined as M[i, j, n] = j + n*(i - 1) if i is odd and M[i, j, n] = n*i - j + 1 if i is even (see the examples below).

The rows of even indices of the triangle T are made of all the same repeating number.

			n\k|   1   2   3   4   5   6
---+------------------------
1  |   1
2  |   5   5
3  |  14  15  16
4  |  34  34  34  34
5  |  63  64  65  66  67
6  | 111 111 111 111 111 111
...
For n = 1 the matrix M is
  1
with column sum 1.
For n = 2 the matrix M is
  1, 2
  4, 3
with column sums 5, 5.
For n = 3 the matrix M is
  1, 2, 3
  6, 5, 4
  7, 8, 9
with column sums 14, 15, 16.

Stefano Spezia, First 150 rows of the triangle, flattened

Cf. A006003, A000027, A000035, A037270 (row sums).
A317614(n): the trace of the n X n square matrix M.
A074147(n): the elements of the antidiagonal of the n X n square matrix M.
A241016(n): the triangle of the row sums of the n X n square matrix M.
A246697(n): the right diagonal of the triangle T.

A317617 := function(n)
local i, j, t;
for i in [1 .. n] do
   for j in [1 .. i] do
      t := (i^3 + i)/2 + (j - (i + 1)/2)*(i mod 2);
      Print(t, "\t");
   od;
   Print("\n");
od;
end;
A317617(11); # yields sequence in triangular form

Flat(List([1..11],n->List([1..n],k->(n^3+n)/2+(k-(n+1)/2)*(n mod 2)))); # Muniru A Asiru, Aug 24 2018

[[(n^3 + n)/2 + (k - (n + 1)/2)*(n mod 2): k in [1..n]]: n in [1..11]];

a:=(n,k)->(n^3+n)/2+(k-(n+1)/2)*modp(n,2): seq(seq(a(n,k),k=1..n),n=1..11); # Muniru A Asiru, Aug 24 2018

f[n_] := Table[SeriesCoefficient[(x*(x*(5 - 7*y) + x^4*(1 - 2*y) - x^3*(-3 + y) - 3*x^2*(-1 + y) + y))/((-1 + x)^4*(1 + x)^2*(-1 + y)^2), {x, 0, i}, {y, 0, j}], {i, n, n}, {j, 1, n}]; Flatten[Array[f, 11]]
T[i_, j_, n_] := If[OddQ@ i, j + n*(i - 1), n*i - j + 1]; f[n_] := Plus @@@ Transpose[ Table[T[i, j, n], {i, n}, {j, n}]]; Array[f, 11] // Flatten  (* Robert G. Wilson v, Aug 01 2018 *)
f[n_] := Table[SeriesCoefficient[1/4 E^(-x + y) (1 - x - 2 y + E^(2 x) (-1 + 3 x + 6 x^2 + 2 x^3 + 2 y)), {x, 0, i}, {y, 0, j}]*i!*j!, {i, n, n}, {j, 1, n}]; Flatten[Array[f, 11]] (* Stefano Spezia, Jan 10 2019 *)

sjoin(v, j) := apply(sconcat, rest(join(makelist(j, length(v)), v)))$ display_triangle(n) := for i from 1 thru n do disp(sjoin(makelist((i^3+i)/2+(j-(i+1)/2)*mod(i, 2), j, 1, i), " ")); display_triangle(10);

M(i,j,n) = if (i % 2, j + n*(i-1), n*i - j + 1);
T(n, k) = sum(i=1, n, M(i,k,n));
tabl(nn) = for(n=1, nn, for(k=1, n, print1(T(n,k), ", ")); print); \\ Michel Marcus, Aug 09 2018

# by formula
for (n in 1:11){
   t <- c(n, "")
   for(j in 1:n){
      t <- c(t, (n^3+n)/2+(j-(n+1)/2)*(n%%2), "")
   }
   cat(t, "\n")
} # yields sequence in triangular form
(MATLAB and FreeMat)
for(i=1:11);
   for(j=1:i);
      t=(i^3 + i)/2 + (j - (i + 1)/2)*mod(i,2);
      fprintf('%0.f\t', t);
   end
   fprintf('\n');
end % yields sequence in triangular form

T(n, k) = A006003(n) + (k - (A000027(n) + 1)/2)*A000035(n).
G.f.: x*(x*(5 - 7*y) + x^4*(1 - 2*y) - x^3*(- 3 + y) - 3*x^2*(- 1 + y) + y)/((-1 + x)^4*(1 + x)^2*(-1 + y)^2).
E.g.f.: (1/4)*exp(-x + y)*(1 - x - 2*y + exp(2*x)*(-1 + 3*x + 6*x^2 + 2*x^3 + 2*y)). - Stefano Spezia, Jan 10 2019

A373330 a(n) is the difference between T = A000217(n^2) and the greatest square not exceeding T.

Original entry on oeis.org

0, 0, 1, 9, 15, 1, 41, 0, 55, 72, 9, 156, 36, 204, 262, 144, 135, 289, 209, 316, 111, 117, 406, 309, 527, 261, 342, 860, 804, 36, 954, 1200, 624, 605, 1257, 969, 1400, 741, 849, 1856, 1639, 0, 1721, 2076, 855, 701, 1770, 1101, 1719, 397, 426, 1980, 1416, 2449, 1142

Offset: 0

Hugo Pfoertner, Jun 02 2024

Michael De Vlieger, Table of n, a(n) for n = 0..9998
Hugo Pfoertner, Logarithmic plot of a(n) vs n, n <= 10^5, lower envelope of terms > 0 shown in red, zoom for details.

Cf. A000217, A000290, A002315, A037270, A061288, A373329, A373333.

A373331 and A373332 are the coordinates of the observed lower envelope of this sequence.

Array[PolygonalNumber[#^2] - Floor[Sqrt[(#^4 + #^2)/2]]^2 &, 55, 0] (* Michael De Vlieger, Jun 02 2024 *)

a(n) = my(T=(n^4+n^2)/2); T-sqrtint(T)^2

from sympy import integer_nthroot
def A373330(n): return (T:=(n**4 + n**2) // 2)-(integer_nthroot(T,2)[0])**2
# Karl-Heinz Hofmann, Jul 01 2024

a(n) = A000217(n^2) - A373329(n)^2.

a(A002315(n)) = 0.

cp's OEIS Frontend

A173130 a(n) = Cosh[(2 n - 1) ArcCosh[n]].

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A173131 a(n) = (Cosh[(2n-1)ArcSinh[n]])^2.

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A173133 a(n) = Sinh[(2n-1) ArcSinh[n]].

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A241016 Triangle read by rows: T(n, k) = sum of k-th row of n X n square filled with the numbers 1 through n^2 reading across rows left-to-right.

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A283030 Number of inequivalent 5 X 5 matrices with entries in {1,2,3,...,n} up to row permutations.

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A331351 Number of achiral colorings of the edges of a cube or regular octahedron.

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A173134 a(n) = Sinh[(2n-1)ArcCosh[n]]^2.

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

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