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 1-7 of 7 results.

A181246 Number of n X 3 binary matrices with no 2 X 2 block having four 1's.

Original entry on oeis.org

8, 57, 417, 3032, 22077, 160697, 1169792, 8515337, 61986457, 451223152, 3284626797, 23910060017, 174050512312, 1266980540057, 9222838063377, 67136581219272, 488712965249117, 3557529413370537, 25896623226618032
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Comments

Column 3 of A181253.

Crossrefs

Cf. A181253.

Formula

Empirical: a(n) = 6*a(n-1) + 10*a(n-2) - 5*a(n-3).
Empirical g.f.: x*(8 + 9*x - 5*x^2) / (1 - 6*x - 10*x^2 + 5*x^3). - Colin Barker, Mar 26 2018

A181247 Number of n X 4 binary matrices with no 2 X 2 block having four 1's.

Original entry on oeis.org

16, 216, 3032, 42176, 587920, 8191392, 114142368, 1590466304, 22161786304, 308805072256, 4302929532288, 59957567962112, 835456401197312, 11641356029819392, 162212139560176128, 2260284639281590272
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Comments

Column 4 of A181253.

Crossrefs

Cf. A181253.

Formula

Empirical: a(n) = 10*a(n-1) + 54*a(n-2) + 16*a(n-3) - 64*a(n-4).
Empirical g.f.: 8*x*(2 + 7*x + x^2 - 8*x^3) / (1 - 10*x - 54*x^2 - 16*x^3 + 64*x^4). - Colin Barker, Mar 26 2018

A181248 Number of nX5 binary matrices with no 2X2 block having four 1's.

Original entry on oeis.org

32, 819, 22077, 587920, 15701273, 419045269, 11185495872, 298561305103, 7969215344753, 212714316418464, 5677773794982333, 151551208150533689, 4045206823611571168, 107974712600136074779, 2882062422625926933109
Offset: 1

Views

Author

R. H. Hardin Oct 10 2010

Keywords

Comments

Column 5 of A181253

Formula

Empirical: a(n)=20*a(n-1)+188*a(n-2)-192*a(n-3)-1660*a(n-4)+2804*a(n-5)-507*a(n-6)-624*a(n-7)

A181249 Number of nX6 binary matrices with no 2X2 block having four 1's.

Original entry on oeis.org

64, 3105, 160697, 8191392, 419045269, 21418970801, 1095020802848, 55979092539545, 2861765993703849, 146298965997241152, 7479088292930771309, 382345515897175884705, 19546245848381921238016, 999242067236417336040593
Offset: 1

Views

Author

R. H. Hardin Oct 10 2010

Keywords

Comments

Column 6 of A181253

Formula

Empirical: a(n)=33*a(n-1)+908*a(n-2)+1687*a(n-3)-37947*a(n-4)-16572*a(n-5)+513993*a(n-6)-663729*a(n-7)-486540*a(n-8)+617409*a(n-9)+191835*a(n-10)-49140*a(n-11)

A181250 Number of n X 7 binary matrices with no 2 X 2 block having four 1's.

Original entry on oeis.org

128, 11772, 1169792, 114142368, 11185495872, 1095020802848, 107224417436160, 10498818149889952, 1027999596778673856, 100657027683287334528, 9855884014448812881664, 965043721129265059674752
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Comments

Column 7 of A181253.

Crossrefs

Cf. A181253.

Formula

Empirical: a(n)=68*a(n-1)+3106*a(n-2)-10300*a(n-3)-731184*a(n-4)+3930848*a(n-5)+47046600*a(n-6)-471525808*a(n-7)+1012118640*a(n-8)+2396096576*a(n-9)-9445394304*a(n-10)-4382776896*a(n-11)+29415041536*a(n-12)+8676097024*a(n-13)-36065068032*a(n-14)-14871987200*a(n-15)+10138337280*a(n-16)+2907136000*a(n-17)-1119682560*a(n-18).

A181251 Number of n X 8 binary matrices with no 2 X 2 block having four 1's.

Original entry on oeis.org

256, 44631, 8515337, 1590466304, 298561305103, 55979092539545, 10498818149889952, 1968910887183791359, 369248337357375835969, 69248348058920729348864, 12986755671559657328386775
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Comments

Column 8 of A181253.

Crossrefs

Cf. A181253.

Formula

Empirical: a(n)=113*a(n-1)+13879*a(n-2)+91506*a(n-3)-13567062*a(n-4)-45766270*a(n-5)+5948333641*a(n-6)-25692714697*a(n-7)-932093986319*a(n-8)+9749317949468*a(n-9)+6293344318720*a(n-10)-400364584466276*a(n-11)+544975615003201*a(n-12)+8011657063605359*a(n-13)-12237642139437047*a(n-14)-98976024373360414*a(n-15)+87321080164809042*a(n-16)+743714645681446194*a(n-17)-21941742884172873*a(n-18)-2838216189512832023*a(n-19)-1559534908222727729*a(n-20)+4451110188283146640*a(n-21)+3110756142589939204*a(n-22)-3806251587192837456*a(n-23)-2258950594106495040*a(n-24)+1998716044109621760*a(n-25)+565195437997056000*a(n-26)-541032812384256000*a(n-27)+28184753405952000*a(n-28)+19493777571840000*a(n-29).

A181252 Number of n X 9 binary matrices with no 2 X 2 block having four 1's.

Original entry on oeis.org

512, 169209, 61986457, 22161786304, 7969215344753, 2861765993703849, 1027999596778673856, 369248337357375835969, 132633131268024896655873, 47641303155727829675539968, 17112587585474467714330327353
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Comments

Column 9 of A181253.

Crossrefs

Cf. A181253.

Programs

  • Maple
    for i from 1 to 512 do Configs[i]:= convert(2^9+i-1,base,2)[1..9] od:
    Compatible:= proc(i,j)
    if `and`(seq(evalb(Configs[i][k] + Configs[i][k+1] + Configs[j][k]+Configs[j][k+1] < 4), k=1..8)) then 1 else 0 fi
    end proc:
    T:= Matrix(512,512,Compatible):
    v:= Vector(512,1):
    TV[0]:= v:
    for nn from 1 to 23 do TV[nn]:= T . TV[nn-1] od:
    seq(v^%T . TV[n],n=0..23); # Robert Israel, Apr 02 2020

Formula

Linear recurrence of order 48: see link. - Robert Israel, Apr 02 2020
Showing 1-7 of 7 results.