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 1-8 of 8 results.

A304004 Number of n X 2 0..1 arrays with every element unequal to 0, 2, 3 or 5 king-move adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 4, 7, 13, 26, 49, 99, 194, 387, 773, 1538, 3081, 6147, 12298, 24587, 49157, 98330, 196609, 393251, 786450, 1572883, 3145797, 6291442, 12583033, 25165827, 50331738, 100663451, 201326533, 402653578, 805306225, 1610613155, 3221225698
Offset: 1

Views

Author

R. H. Hardin, May 04 2018

Keywords

Comments

Column 2 of A304010.

Examples

			Some solutions for n=5
..0..0. .0..1. .0..1. .0..1. .0..1. .0..1. .0..1. .0..0. .0..1. .0..1
..1..1. .0..1. .1..0. .0..1. .1..0. .1..0. .1..0. .0..0. .1..0. .0..1
..1..1. .0..1. .0..1. .1..0. .0..1. .1..0. .0..1. .0..0. .1..0. .1..0
..1..1. .0..1. .0..1. .1..0. .0..1. .1..0. .1..0. .0..0. .0..1. .0..1
..0..0. .0..1. .0..1. .1..0. .1..0. .0..1. .0..1. .0..0. .0..1. .0..1
		

Crossrefs

Cf. A304010.

Formula

Empirical: a(n) = a(n-1) +3*a(n-2) -4*a(n-4) for n > 5.

A304111 Partial sums of f(n) = (-1)^(1-A304109(n)).

Original entry on oeis.org

0, 1, 2, 3, 2, 1, 2, 3, 2, 3, 2, 3, 2, 3, 4, 3, 2, 1, 2, 3, 2, 1, 2, 3, 2, 3, 4, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 4, 3, 2, 3, 2, 3, 2, 1, 2, 3, 2, 3, 4, 3, 2, 3, 2, 3, 2, 1, 2, 3, 2, 3, 4, 3, 2, 1, 2, 3, 2, 1, 2, 3, 2, 3, 4, 3, 2, 3, 2, 3, 2, 1, 2, 3, 2, 1, 2, 3, 2, 3, 2, 3, 2, 3, 4, 3, 2, 3, 4, 3, 2, 3, 2, 3, 2, 1, 2, 1, 0, 1, 2, 3, 2, 3, 2, 3, 2, 3, 4, 3, 2
Offset: 0

Views

Author

Antti Karttunen, May 13 2018

Keywords

Comments

Start from the initial value a(0) = 0, after which, for n > 0, each successive term a(n) is either one more or one less than the previous term a(n-1), depending on whether the binary expansion of n encodes a squarefree (0,1)-polynomial when the factorization is done in polynomial ring GF(2)[X], or whether it encodes a polynomial where at least one of its irreducible divisors occurs more than once.
The first negative term occurs as a(153) = -1. See also comments at A304010.

Crossrefs

Programs

  • PARI
    up_to = 128;
    A304109(n) = { my(fm=factor(Pol(binary(n))*Mod(1, 2))); for(k=1, #fm~, if(fm[k, 2] > 1, return(0))); (1); };
    prepare_v304110(up_to) = { my(v=vector(up_to), c=0); for(n=1, up_to, c += A304109(n); v[n] = c); (v); };
    v304110 = prepare_v304110(up_to);
    A304110(n) = v304110[n];
    A304111(n) = ((2*A304110(n)) - n);
    \\ Or just as:
    c=0; for(n=0, up_to, if(n>0, c+=((-1)^(1-A304109(n)))); print1(c, ", "));

Formula

a(0) = 0, and for n > 0, a(n) = a(n-1) + (-1)^(1-A304109(n)).
For n >= 1, a(n) = (2*A304110(n)) - n.

A304005 Number of nX3 0..1 arrays with every element unequal to 0, 2, 3 or 5 king-move adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 7, 13, 21, 27, 53, 99, 197, 371, 713, 1365, 2645, 5105, 9857, 19079, 36861, 71379, 138165, 267465, 518201, 1003521, 1944649, 3767939, 7302057, 14153291, 27432325, 53179669, 103092661, 199871009, 387518385, 751360183, 1456897269, 2824988675
Offset: 1

Views

Author

R. H. Hardin, May 04 2018

Keywords

Comments

Column 3 of A304010.

Examples

			Some solutions for n=5
..0..1..0. .0..1..0. .0..0..0. .0..1..0. .0..0..0. .0..0..0. .0..0..0
..0..1..1. .1..1..1. .0..0..0. .1..1..1. .1..1..1. .1..1..1. .0..0..0
..1..0..0. .0..0..0. .0..0..0. .1..0..1. .1..1..1. .0..1..0. .0..0..0
..1..1..0. .0..0..0. .0..0..0. .0..0..0. .1..1..1. .0..0..0. .1..1..1
..0..1..0. .1..1..1. .1..1..1. .1..1..1. .0..0..0. .1..0..1. .0..1..0
		

Crossrefs

Cf. A304010.

Formula

Empirical: a(n) = a(n-1) +5*a(n-2) -a(n-3) -12*a(n-4) -2*a(n-5) +10*a(n-6) +2*a(n-7) +a(n-8) +7*a(n-9) -3*a(n-10) -19*a(n-11) -2*a(n-12) +2*a(n-13) -4*a(n-14) +10*a(n-15) +6*a(n-16) for n>17

A304006 Number of n X 4 0..1 arrays with every element unequal to 0, 2, 3 or 5 king-move adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 13, 21, 26, 64, 115, 211, 439, 870, 1725, 3513, 7141, 14372, 29438, 60518, 123439, 253860, 523477, 1075787, 2216143, 4575316, 9438222, 19480290, 40253428, 83178619, 171897255, 355448881, 735100437, 1520380599, 3145360038, 6508033432
Offset: 1

Views

Author

R. H. Hardin, May 04 2018

Keywords

Comments

Column 4 of A304010.

Examples

			Some solutions for n=5
..0..0..1..1. .0..1..1..1. .0..1..1..0. .0..1..0..0. .0..0..0..0
..0..0..1..1. .1..0..0..0. .0..1..0..1. .1..0..1..1. .0..0..0..0
..0..0..1..1. .0..1..1..0. .0..0..1..0. .1..0..1..0. .1..1..1..1
..0..0..1..1. .0..1..0..1. .0..1..0..0. .0..1..0..0. .1..1..1..1
..0..0..1..1. .1..0..0..1. .0..1..1..1. .1..0..0..1. .1..1..1..1
		

Crossrefs

Cf. A304010.

Formula

Empirical: a(n) = 5*a(n-1) -6*a(n-2) -9*a(n-4) +8*a(n-5) +36*a(n-6) -29*a(n-7) +34*a(n-8) -88*a(n-9) +8*a(n-10) -70*a(n-11) +205*a(n-12) +66*a(n-13) -377*a(n-14) -29*a(n-15) +420*a(n-16) +897*a(n-17) -1329*a(n-18) -1792*a(n-19) +3267*a(n-20) +1953*a(n-21) -3000*a(n-22) -1986*a(n-23) -1836*a(n-24) +4857*a(n-25) -812*a(n-26) +2460*a(n-27) -5658*a(n-28) -21869*a(n-29) +5879*a(n-30) +37979*a(n-31) +39222*a(n-32) -53345*a(n-33) -60350*a(n-34) +80033*a(n-35) +55646*a(n-36) -80249*a(n-37) -99116*a(n-38) +97246*a(n-39) +113723*a(n-40) -115592*a(n-41) -82690*a(n-42) +63249*a(n-43) +23806*a(n-44) -67251*a(n-45) +52726*a(n-46) +64947*a(n-47) -59223*a(n-48) +4895*a(n-49) +22611*a(n-50) -5950*a(n-51) +1369*a(n-52) +5125*a(n-53) -13309*a(n-54) -19653*a(n-55) +5627*a(n-56) +2405*a(n-57) +1342*a(n-58) +2478*a(n-59) +2088*a(n-60) +435*a(n-61) -1017*a(n-62) -263*a(n-63) -116*a(n-64) +64*a(n-65) -96*a(n-66) +48*a(n-67) for n>70.

A304007 Number of nX5 0..1 arrays with every element unequal to 0, 2, 3 or 5 king-move adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 26, 27, 64, 137, 271, 655, 1412, 3245, 7809, 17290, 40682, 93292, 216048, 499755, 1162587, 2685521, 6238096, 14489376, 33631721, 78120529, 181638185, 422198419, 981730209, 2284138522, 5314049218, 12366970040, 28787274304, 67017999388
Offset: 1

Views

Author

R. H. Hardin, May 04 2018

Keywords

Comments

Column 5 of A304010.

Examples

			Some solutions for n=5
..0..0..0..0..0. .0..0..0..1..1. .0..1..0..1..0. .0..0..1..1..1
..1..1..0..1..1. .1..1..1..0..0. .0..1..1..1..0. .1..1..0..0..0
..0..1..1..1..0. .0..1..0..0..0. .0..0..1..0..0. .1..0..0..0..0
..1..1..0..1..1. .1..1..0..1..1. .0..1..1..1..0. .0..0..0..1..1
..0..0..0..0..0. .0..0..1..1..0. .0..1..0..1..0. .1..0..1..1..0
		

Crossrefs

Cf. A304010.

A304008 Number of nX6 0..1 arrays with every element unequal to 0, 2, 3 or 5 king-move adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 49, 53, 115, 271, 538, 1458, 2973, 7826, 19113, 47074, 115148, 283156, 698411, 1720946, 4258788, 10518418, 26019796, 64391560, 159345205, 394533973, 976872015, 2419079852, 5991435758, 14839400772, 36760610050, 91064615465
Offset: 1

Views

Author

R. H. Hardin, May 04 2018

Keywords

Comments

Column 6 of A304010.

Examples

			Some solutions for n=5
..0..1..0..0..0..1. .0..1..1..1..0..1. .0..1..0..1..0..1. .0..0..0..0..1..0
..1..1..1..0..1..0. .1..0..0..1..0..0. .0..1..1..1..0..0. .1..1..0..1..1..0
..0..1..1..1..1..0. .1..1..0..0..1..1. .0..0..1..1..1..0. .1..0..1..0..0..1
..0..0..1..1..0..0. .0..0..1..0..0..1. .0..1..1..0..1..0. .0..0..1..0..1..1
..1..0..1..1..0..1. .1..0..1..1..1..0. .1..0..0..0..0..1. .1..0..1..1..0..0
		

Crossrefs

Cf. A304010.

A304009 Number of nX7 0..1 arrays with every element unequal to 0, 2, 3 or 5 king-move adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 99, 99, 211, 655, 1458, 4224, 10633, 28365, 75175, 201031, 544217, 1452266, 3908208, 10505646, 28266755, 76097248, 204983456, 552420015, 1488384837, 4011805443, 10816167549, 29162780211, 78639733211, 212076547630
Offset: 1

Views

Author

R. H. Hardin, May 04 2018

Keywords

Comments

Column 7 of A304010.

Examples

			Some solutions for n=5
..0..0..0..0..1..1..1. .0..0..0..0..0..0..1. .0..1..1..0..1..1..0
..1..1..1..0..1..1..1. .1..1..0..1..1..1..0. .0..1..0..0..0..1..0
..0..1..0..1..1..1..1. .0..1..1..1..0..0..1. .1..0..0..0..0..0..1
..0..0..0..1..1..0..0. .1..1..1..0..1..0..1. .0..1..0..0..0..1..0
..1..0..1..1..0..0..1. .0..1..0..0..1..1..0. .1..0..1..1..1..0..1
		

Crossrefs

Cf. A304010.

A304003 Number of n X n 0..1 arrays with every element unequal to 0, 2, 3 or 5 king-move adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 4, 13, 26, 137, 538, 4224, 30468, 264104, 2993696, 40315467
Offset: 1

Views

Author

R. H. Hardin, May 04 2018

Keywords

Comments

Diagonal of A304010.

Examples

			Some solutions for n=5
..0..0..1..1..0. .0..1..1..1..1. .0..0..0..1..1. .0..0..1..1..1
..1..1..0..0..1. .0..1..1..1..1. .0..0..0..1..1. .0..0..1..1..1
..1..1..1..0..1. .0..1..1..1..1. .0..0..0..0..0. .0..0..0..0..0
..0..0..1..0..1. .0..1..1..1..1. .1..1..1..0..0. .1..1..0..0..0
..1..0..0..1..0. .0..1..1..1..1. .1..1..1..0..0. .1..1..0..0..0
		

Crossrefs

Cf. A304010.
Showing 1-8 of 8 results.