A052398 Duplicate of A047890.
1, 2, 6, 24, 120, 719, 5003, 39429, 344837, 3291590, 33835114, 370531683
Offset: 0
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.
G.f. = 1 + x + 2*x^2 + 6*x^3 + 24*x^4 + 119*x^5 + 694*x^6 + 4582*x^7 + ...
A:=rsolve({a(0) = 1, a(1) = 1, (n^3 + 16*n^2 + 85*n + 150)*a(n + 2) = (20*n^3 + 182*n^2 + 510*n + 428)*a(n + 1) - (64*n^3 + 256*n^2 + 320*n +128)*a(n)}, a(n), makeproc): # Alec Mihailovs (alec(AT)mihailovs.com), Aug 14 2005
Flatten[{1,RecurrenceTable[{64*(-1+n)^2*n*a[-2+n]-2*(-12 + 11*n + 31*n^2 + 10*n^3)*a[-1+n] + (3+n)^2*(4+n)*a[n]==0,a[1]==1,a[2]==2},a,{n,20}]}] (* Vaclav Kotesovec, Sep 10 2014 *)
{a(n) = my(v); if( n<2, n>=0, v = vector(n+1, k, 1); for(k=2, n, v[k+1] = ((20*k^3 + 62*k^2 + 22*k - 24) * v[k] - 64*k*(k-1)^2 * v[k-1]) / ((k+3)^2 * (k+4))); v[n+1])}; /* Michael Somos, Apr 19 2015 */
A(4,2) = 14 because 14 permutations of {1,2,3,4} do not contain an increasing subsequence of length > 2: 1432, 2143, 2413, 2431, 3142, 3214, 3241, 3412, 3421, 4132, 4213, 4231, 4312, 4321. Permutation 1423 is not counted because it contains the noncontiguous increasing subsequence 123. A(4,2) = 14 = 2^2 + 3^2 + 1^2 because the partitions of 4 with <= 2 parts are [2,2], [3,1], [4] with 2, 3, 1 standard Young tableaux, respectively: +------+ +------+ +---------+ +---------+ +---------+ +------------+ | 1 3 | | 1 2 | | 1 3 4 | | 1 2 4 | | 1 2 3 | | 1 2 3 4 | | 2 4 | | 3 4 | | 2 .-----+ | 3 .-----+ | 4 .-----+ +------------+ +------+ +------+ +---+ +---+ +---+ Square array A(n,k) begins: 1, 1, 1, 1, 1, 1, 1, 1, ... 0, 1, 1, 1, 1, 1, 1, 1, ... 0, 1, 2, 2, 2, 2, 2, 2, ... 0, 1, 5, 6, 6, 6, 6, 6, ... 0, 1, 14, 23, 24, 24, 24, 24, ... 0, 1, 42, 103, 119, 120, 120, 120, ... 0, 1, 132, 513, 694, 719, 720, 720, ... 0, 1, 429, 2761, 4582, 5003, 5039, 5040, ...
h:= proc(l) local n; n:=nops(l); add(i, i=l)! /mul(mul(1+l[i]-j +add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n) end: g:= (n, i, l)-> `if`(n=0 or i=1, h([l[], 1$n])^2, `if`(i<1, 0, add(g(n-i*j, i-1, [l[], i$j]), j=0..n/i))): A:= (n, k)-> `if`(k>=n, n!, g(n, k, [])): seq(seq(A(n, d-n), n=0..d), d=0..14);
h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]! / Product[Product[1+l[[i]]-j + Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}]]; g[n_, i_, l_] := If[n == 0 || i == 1, h[Join[l, Array[1&, n]]]^2, If[i < 1, 0, Sum[g[n - i*j, i-1, Join[l, Array[i&, j]]], {j, 0, n/i}]]]; A[n_, k_] := If[k >= n, n!, g[n, k, {}]]; Table [Table [A[n, d-n], {n, 0, d}], {d, 0, 14}] // Flatten (* Jean-François Alcover, Dec 09 2013, translated from Maple *)
h:= proc(l) local n; n:=nops(l); add(i, i=l)! /mul(mul(1+l[i]-j +add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n) end: g:= proc(n, i, l) option remember; `if`(n=0, h(l)^2, `if`(i<1, 0, `if`(i=1, h([l[], 1$n])^2, g(n, i-1, l)+ `if`(i>n, 0, g(n-i, i, [l[], i]))))) end: a:= n-> g(n, 6, []): seq(a(n), n=0..25); # Alois P. Heinz, Apr 10 2012 # second Maple program a:= proc(n) option remember; `if`(n<7, n!, ((56*n^5-9408+11032*n+19028*n^2+7360*n^3+1092*n^4)*a(n-1) -4*(196*n^3+1608*n^2+3167*n+444)*(n-1)^2*a(n-2) +1152*(2*n+3)*(n-1)^2*(n-2)^2*a(n-3))/ ((n+9)*(n+8)^2*(n+5)^2)) end: seq(a(n), n=0..30); # Alois P. Heinz, Sep 26 2012
h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]!/Product[Product[1+l[[i]]-j+Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}]]; g[n_, i_, l_] := If[n == 0 || i == 1, h[Join[l, Array[1&, n]]]^2, If[i<1, 0, Sum[g[n-i*j, i-1, Join[l, Array[i&, j]]], {j, 0, n/i}]]]; a[n_, k_] := If[k >= n, n!, g[n, k, {}]]; Table[a[n, 6], {n, 0, 30}] (* Jean-François Alcover, Mar 11 2014, after Alois P. Heinz *)
a:= proc(n) option remember; `if`(n<8, n!, ((-343035+429858*n +238440*n^3+38958*n^4+634756*n^2+2940*n^5+84*n^6)*a(n-1) -(1974*n^4+36336*n^3+213240*n^2+407840*n+82425)*(n-1)^2*a(n-2) +2*(49875+42646*n+6458*n^2)*(n-1)^2*(n-2)^2*a(n-3) -11025*(n-1)^2*(n-2)^2*(n-3)^2*a(n-4))/ ((n+6)^2*(n+10)^2*(n+12)^2)) end: seq (a(n), n=1..30); # Alois P. Heinz, Sep 26 2012
h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]!/Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}] ]; g[n_, i_, l_] := If[n==0 || i==1, h[Join[l, Array[1&, n]]]^2, If[i<1, 0, Sum[g[n - i*j, i-1, Join[l, Array[i&, j]]], {j, 0, n/i}]]]; a[n_] := If[n <= 7, n!, g[n, 7, {}]]; Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Feb 24 2016, after Alois P. Heinz (A214015) *)
a:= proc(n) option remember; `if`(n<4, n!, (-147456*(n+4)*(n-1)^2*(n-2)^2*(n-3)^2*a(n-4) +128*(33876+30709*n+6687*n^2+410*n^3)*(n-1)^2*(n-2)^2*a(n-3) -4*(1092*n^5+37140*n^4+455667*n^3+2387171*n^2+4649270*n+1206000)* (n-1)^2*a(n-2) +(-17075520+(22488312+(29223280+(10509820+(1764252+ (154164+(6804+120*n)*n)*n)*n)*n)*n)*n)*a(n-1))/ ((n+16)*(n+7)^2*(n+15)^2*(n+12)^2)) end: seq(a(n), n=1..30); # Alois P. Heinz, Sep 28 2012
h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]!/Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}] ]; g[n_, i_, l_] := If[n==0 || i==1, h[Join[l, Array[1&, n]]]^2, If[i < 1, 0, Sum[g[n - i*j, i-1, Join[l, Array[i&, j]]], {j, 0, n/i}]]]; a[n_] := If[n <= 8, n!, g[n, 8, {}]]; Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Feb 24 2016, after Alois P. Heinz (A214015) *)
a:= proc(n) option remember; `if`(n<5, n!, ((-1110790863+(1520978576+(1772290401+(607308786+ (101671498+(9464664+(500874+(14124+165*n)*n)*n)*n)*n)*n)*n)*n)*a(n-1) -(1129886062*n+559908333*n^2+111239576*n^3+10655238*n^4+8778*n^6 +491700*n^5 +353895381)*(n-1)^2*a(n-2) +(258011271+234066216*n +58221266*n^2+5463876*n^3 +172810*n^4)*(n-1)^2*(n-2)^2*a(n-3) -9*(4070430+1504292*n+117469*n^2)* (n-1)^2*(n-2)^2*(n-3)^2*a(n-4) +893025*(n-1)^2*(n-2)^2*(n-3)^2*(n-4)^2*a(n-5)) / ((n+20)^2*(n+8)^2*(n+18)^2*(n+14)^2)) end: seq(a(n), n=0..30); # Alois P. Heinz, Oct 10 2012
h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]!/Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}]]; g[n_, i_, l_] := If[n==0 || i==1, h[Join[l, Array[1 &, n]]]^2, If[i < 1, 0, Sum[g[n - i*j, i - 1, Join[l, Array[i &, j]]], {j, 0, n/i}]]]; a[n_] := If[n <= 9, n!, g[n, 9, {}]]; Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Feb 24 2016, after Alois P. Heinz (A214015) *)
h:= proc(l) local n; n:=nops(l); add(i, i=l)! /mul(mul(1+l[i]-j +add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n) end: g:= proc(n, i, l) `if`(n=0 or i=1, h([l[], 1$n])^2, `if`(i<1, 0, add(g(n-i*j, i-1, [l[], i$j]), j=0..n/i))) end: a:= n-> n! -g(n, 5, []): seq(a(n), n=6..30); # Alois P. Heinz, Jul 05 2012 # second Maple program a:= proc(n) option remember; `if`(n<6, 0, `if`(n=6, 1, ((2475-4819*n^2-2985*n+175*n^4-1021*n^3+n^6+49*n^5)*a(n-1) -(35*n^4+441*n^3-845*n^2-4147*n-489)*(n-1)^2*a(n-2) +(-1668+329*n+259*n^2)*(n-1)^2*(n-2)^2*a(n-3) -225*(n-1)^2*(n-2)^2*(n-3)^2*a(n-4))/ ((n-6)*(n+6)^2*(n+4)^2))) end: seq(a(n), n=6..30); # Alois P. Heinz, Sep 26 2012
h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]!/Product[Product[1+l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}]]; g[n_, i_, l_] := If[n == 0 || i === 1, h[Join[l, Array[1 &, n]]]^2, If[i < 1, 0, Sum[g[n - i*j, i - 1, Join[l, Array[i &, j]]], {j, 0, n/i}]]]; a[n_] := n! - g[n, 5, {}]; Table[a[n], {n, 6, 30}] (* Jean-François Alcover, Jun 19 2018, from first Maple program *)
h:= proc(l) local n; n:=nops(l); add(i, i=l)! / mul(mul(1+l[i]-j +add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n) end: g:= proc(n, i, l) option remember; `if`(n=0, h(l)^2, `if`(i<1, 0, `if`(i=1, h([l[], 1$n])^2, g(n, i-1, l)+ `if`(i>n, 0, g(n-i, i, [l[], i]))))) end: a:= n-> g(n, 10, []): seq(a(n), n=0..25); # Vaclav Kotesovec, Sep 10 2014, after Alois P. Heinz
RecurrenceTable[{-7372800*(-4 + n)^2*(-3 + n)^2*(-2 + n)^2*(-1 + n)^2*(15 + 2*n)*a[-5 + n] + 256*(-3 + n)^2*(-2 + n)^2*(-1 + n)^2*(11018760 + 4743323*n + 577824*n^2 + 21076*n^3)*a[-4 + n]-8*(-2 + n)^2*(-1 + n)^2*(2488711560 + 2208119423*n + 580006399*n^2 + 64938154*n^3 + 3273732*n^4 + 61160*n^5)*a[-3 + n] + 4*(-1 + n)^2*(8002290720 + 21962910556*n + 10433770264*n^2 + 2088552609*n^3 + 215646686*n^4 + 12084237*n^5 + 349536*n^6 + 4092*n^7)*a[-2 + n]-2*(-45705600000 + 64584000000*n + 68412531600*n^2 + 22314826244*n^3 + 3672058745*n^4 + 350428790*n^5 + 20286926*n^6 + 704088*n^7 + 13497*n^8 + 110*n^9)*a[-1 + n] + (9 + n)^2*(16 + n)^2*(21 + n)^2*(24 + n)^2*(25 + n)*a[n]==0,a[1]==1,a[2]==2,a[3]==6,a[4]==24,a[5]==120},a,{n,1,20}] (* Vaclav Kotesovec, Sep 10 2014 *)
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