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 1-10 of 11 results. Next

A181253 T(n,k)=Number of nXk binary matrices with no 2X2 block having four 1's.

Original entry on oeis.org

2, 4, 4, 8, 15, 8, 16, 57, 57, 16, 32, 216, 417, 216, 32, 64, 819, 3032, 3032, 819, 64, 128, 3105, 22077, 42176, 22077, 3105, 128, 256, 11772, 160697, 587920, 587920, 160697, 11772, 256, 512, 44631, 1169792, 8191392, 15701273, 8191392, 1169792, 44631, 512
Offset: 1

Views

Author

R. H. Hardin, Oct 10 2010

Keywords

Examples

			Table starts
....2......4.........8...........16..............32.................64
....4.....15........57..........216.............819...............3105
....8.....57.......417.........3032...........22077.............160697
...16....216......3032........42176..........587920............8191392
...32....819.....22077.......587920........15701273..........419045269
...64...3105....160697......8191392.......419045269........21418970801
..128..11772...1169792....114142368.....11185495872......1095020802848
..256..44631...8515337...1590466304....298561305103.....55979092539545
..512.169209..61986457..22161786304...7969215344753...2861765993703849
.1024.641520.451223152.308805072256.212714316418464.146298965997241152
		

Crossrefs

Diagonal is A139810.
Column 2 is A125145.

Formula

Empirical column 1: a(n)=2*a(n-1)
Empirical column 2: a(n)=3*a(n-1)+3*a(n-2)
Empirical column 3: a(n)=6*a(n-1)+10*a(n-2)-5*a(n-3)
Empirical column 4: a(n)=10*a(n-1)+54*a(n-2)+16*a(n-3)-64*a(n-4)
Empirical column 5: 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)
Empirical column 6: 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)
Empirical column 7: 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)
Empirical column 8: 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)

A140304 Number of n X n binary matrices with no more than one 1 in any 3 X 3 sub-block.

Original entry on oeis.org

1, 2, 5, 10, 60, 437, 2875, 36409, 704468, 14783959, 461938624, 22488554884, 1378748967395, 115759328877461, 14408020654986447, 2435526103569141336, 559083220302137929773, 182904062593977747117174, 83283166161035345074485948, 52012981990902321891650583747, 45449967513840995133445585972949
Offset: 0

Views

Author

R. H. Hardin, May 27 2008

Keywords

Crossrefs

Cf. A139810. Row sums of A276171.

Programs

  • Mathematica
    $RecursionLimit = 10^4;
    b[n_, l_] := b[n, l] = Module[{k, m}, m = Min[l]; Which[n < 3, 1, m > 0, b[n - m, l - m], True, k = 1; While[l[[k]] > 0, k++]; b[n, ReplacePart[l, k -> 1]] + Expand[If[k + 1 < Length[l] && l[[k + 1 ;; k + 2]] == {0, 0}, b[n, ReplacePart[l, {k -> 3, k + 1 -> 3, k + 2 -> 3}]]*x, 0]]]];
    a[n_] := a[n] = Function[p, Sum[Coefficient[p, x, i], {i, 0, Exponent[p, x]}]][b[n + 2, Table[0, n + 2]]];
    Table[Print["a(", n, ") = ", a[n]]; a[n], {n, 0, 15}] (* Jean-François Alcover, Nov 11 2017, after Alois P. Heinz *)

A140314 Number of n X n binary matrices containing no more than two 1's in any 2 X 2 subblock.

Original entry on oeis.org

1, 2, 11, 195, 8969, 1232795, 471487297, 516844071813, 1603508113421239, 14148460147460008963, 354360105981877906958557, 25210728065407321182797745205, 5093486498660018140333056634922039
Offset: 0

Views

Author

R. H. Hardin, May 25 2008

Keywords

Comments

No more than 1 1 in any 2 X 2 subblock gives A063443.
No more than 3 1's in any 2 X 2 subblock gives A139810.

Crossrefs

A140311 Number of n X n binary matrices containing no more than eight 1s in any 3 X 3 sub-block.

Original entry on oeis.org

1, 2, 16, 511, 65089, 33066176, 66993993728, 541344347284385, 17445985904048740529, 2242340146792849255134720, 1149454044962768236388517543936, 2349989206497316681704056634171383423
Offset: 0

Views

Author

R. H. Hardin, May 27 2008

Keywords

Crossrefs

Cf. A139810.

A140305 Number of n X n binary matrices containing no more than two 1s in any 3 X 3 sub-block.

Original entry on oeis.org

1, 2, 11, 46, 824, 27178, 1020762, 102044420, 20297233254, 6218446852487, 3906297811846469, 4829512709969500388, 10588146860457194561192, 44163637535605999104548698
Offset: 0

Views

Author

R. H. Hardin, May 27 2008

Keywords

Crossrefs

Cf. A139810.

A140306 Number of n X n binary matrices containing at most three 1's in any 3 X 3 sub-block.

Original entry on oeis.org

1, 2, 15, 130, 4852, 456904, 73948482, 35616138799, 43142990277818, 115017363443317954, 771239506285440035857
Offset: 0

Views

Author

R. H. Hardin, May 27 2008

Keywords

Crossrefs

Cf. A139810.

A140307 Number of n X n binary matrices containing at most four 1's in any 3 X 3 sub-block.

Original entry on oeis.org

1, 2, 16, 256, 15982, 3082378, 1476568000, 2280441045555, 10599616558936358, 140380164790852384033
Offset: 0

Views

Author

R. H. Hardin, May 27 2008

Keywords

Crossrefs

Cf. A139810.

A140308 Number of n X n binary matrices containing no more than five 1s in any 3 X 3 sub-block.

Original entry on oeis.org

1, 2, 16, 382, 33940, 10537021, 10478502929, 36396596300106, 433087032815881242, 17394297682298725368562
Offset: 0

Views

Author

R. H. Hardin, May 27 2008

Keywords

Crossrefs

Cf. A139810.

A140309 Number of n X n binary matrices containing no more than six 1s in any 3 X 3 sub-block.

Original entry on oeis.org

1, 2, 16, 466, 51512, 21425198, 32840182186, 188637643581570, 4048457379398984078, 323937479341259299455434, 96758393657902322435446080112
Offset: 0

Views

Author

R. H. Hardin, May 27 2008

Keywords

Crossrefs

Cf. A139810.

A140310 Number of n X n binary matrices containing no more than seven 1s in any 3 X 3 sub-block.

Original entry on oeis.org

1, 2, 16, 502, 61788, 29829353, 56365481377, 417452923577327, 12115365147171963168, 1377708150938828616858899, 613888995116283293759860580312, 1071847970096627711898648239726154442
Offset: 0

Views

Author

R. H. Hardin, May 27 2008

Keywords

Crossrefs

Cf. A139810.
Showing 1-10 of 11 results. Next