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.

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A255292 Number of 2's in expansion of F^n mod 3, where F = 1/x+1+x+1/y+y.

Original entry on oeis.org

0, 0, 9, 0, 0, 37, 9, 45, 44, 0, 0, 45, 0, 0, 177, 37, 185, 156, 9, 45, 72, 45, 225, 228, 44, 220, 573, 0, 0, 45, 0, 0, 185, 45, 225, 220, 0, 0, 225, 0, 0, 877, 177, 885, 716, 37, 185, 256, 185, 925, 788, 156, 780, 2281, 9
Offset: 0

Views

Author

N. J. A. Sloane, Feb 21 2015

Keywords

Comments

A255291 and A255292 together are a mod 3 analog of A072272.

Examples

			The pairs [no. of 1's, no. of 2's] are [1, 0], [5, 0], [4, 9], [5, 0], [25, 0], [12, 37], [4, 9], [20, 45], [69, 44], [5, 0], [25, 0], [20, 45], [25, 0], [125, 0], [52, 177], [12, 37], [60, 185], [281, 156], [4, 9], [20, 45], [97, 72], [20, 45], [100, 225], [353, 228], [69, 44], [345, 220], [448, 573], [5, 0], [25, 0], [20, 45], ...
		

Crossrefs

Programs

  • Maple
    # C3 Counts 1's and 2's
    C3 := proc(f) local c,ix,iy,f2,i,t1,t2,n1,n2;
    f2:=expand(f) mod 3; n1:=0; n2:=0;
    if whattype(f2) = `+` then
    t1:=nops(f2);
    for i from 1 to t1 do t2:=op(i, f2); ix:=degree(t2, x); iy:=degree(t2, y);
    c:=coeff(coeff(t2,x,ix),y,iy);
    if (c mod 3) = 1 then n1:=n1+1; else n2:=n2+1; fi; od: RETURN([n1,n2]);
    else ix:=degree(f2, x); iy:=degree(f2, y);
    c:=coeff(coeff(f2,x,ix),y,iy);
    if (c mod 3) = 1 then n1:=n1+1; else n2:=n2+1; fi; RETURN([n1,n2]);
    fi;
    end;
    F3:=1/x+1+x+1/y+y mod 3;
    g:=(F,n)->expand(F^n) mod 3;
    [seq(C3(g(F3,n))[2],n=0..60)];

A255293 Number of 1's in expansion of F^n mod 3, where F = 1/x+2+x+1/y+y.

Original entry on oeis.org

1, 4, 8, 4, 17, 29, 8, 37, 49, 4, 17, 37, 17, 76, 128, 29, 136, 196, 8, 37, 89, 37, 176, 292, 49, 260, 584, 4, 17, 37, 17, 76, 136, 37, 176, 260, 17, 76, 176, 76, 353, 605, 128, 613, 961, 29, 136, 332, 136, 653, 1105, 196
Offset: 0

Views

Author

N. J. A. Sloane, Feb 21 2015

Keywords

Comments

A255293 and A255294 together are a second mod 3 analog of A072272.

Examples

			The pairs [no. of 1's, no. of 2's] are [1, 0], [4, 1], [8, 5], [4, 1], [17, 8], [29, 20], [8, 5], [37, 28], [49, 64], [4, 1], [17, 8], [37, 28], [17, 8], [76, 49], [128, 101], [29, 20], [136, 109], [196, 241], [8, 5], [37, 28], [89, 80], [37, 28], [176, 149], [292, 289], [49, 64], [260, 305], [584, 437], [4, 1], [17, 8], [37, 28], ...
		

Crossrefs

Programs

  • Maple
    # C3 Counts 1's and 2's
    C3 := proc(f) local c,ix,iy,f2,i,t1,t2,n1,n2;
    f2:=expand(f) mod 3; n1:=0; n2:=0;
    if whattype(f2) = `+` then
    t1:=nops(f2);
    for i from 1 to t1 do t2:=op(i, f2); ix:=degree(t2, x); iy:=degree(t2, y);
    c:=coeff(coeff(t2,x,ix),y,iy);
    if (c mod 3) = 1 then n1:=n1+1; else n2:=n2+1; fi; od: RETURN([n1,n2]);
    else ix:=degree(f2, x); iy:=degree(f2, y);
    c:=coeff(coeff(f2,x,ix),y,iy);
    if (c mod 3) = 1 then n1:=n1+1; else n2:=n2+1; fi; RETURN([n1,n2]);
    fi;
    end;
    F4:=1/x+2+x+1/y+y mod 3;
    g:=(F,n)->expand(F^n) mod 3;
    [seq(C3(g(F4,n))[1],n=0..60)];

A138276 Total number of active nodes of the Rule 150 cellular automaton on an infinite Bethe lattice with coordination number 3 (with a single 1 as initial condition).

Original entry on oeis.org

1, 4, 6, 18, 30, 90, 102, 306, 510, 1530, 1542, 4626, 7110
Offset: 0

Views

Author

Jens Christian Claussen (claussen(AT)theo-physik.uni-kiel.de), Mar 11 2008

Keywords

Comments

See A138277 for the corresponding sequence for a Bethe lattice with coordination number 4.
See A001045 for the corresponding sequence on a 1D lattice (equivalent to a k=2 Bethe lattice); this is based on the Jacobsthal sequence A001045.
See A072272 for the corresponding sequence on a 2D lattice (based on A007483).
Related to Cellular Automata.

Examples

			Let x_0 be the state (0 or 1) of the focal node and x_i the state of every node that is i steps away from the focal node. In time step n=0, all x_i=0 except x_0=1 (start with a single seed). In the next step, x_1=1 as they have 1 neighbor being 1. For n=2, the x_1 nodes have 1 neighbor being 1 (x_0) and
themselves being 1; the sum being 2, modulo 2, resulting in x_1=0. The focal node itself is 1 and has 3 neighbors being 1, sum being 4, modulo 2, resulting in x_0=0. The outmost nodes x_n are always 1.
Thus one has the patterns
x_0, x_1, x_2, ...
1
1 1
0 0 1
0 0 1 1
0 0 1 0 1
0 0 1 1 1 1
0 0 1 0 0 0 1
0 0 1 1 0 0 1 1
0 0 1 0 1 0 1 0 1
0 0 1 1 1 1 1 1 1 1
0 0 1 0 0 0 0 0 0 0 1
After 2 time steps, the x_0 and x_1 stay frozen at zero and the remaining x_i are generated by Rule 60 (or Rule 90 on half lattice spacing).
These nodes have multiplicities 1,3,6,12,24,48,96,192,384,768,...
The sequence then is obtained by
a(n) = x_0(n) + 3 * Sum_{i=1..n} x_i(n) * 2^(i-1)
		

Crossrefs

Formula

The total number of nodes in state 1 after n iterations (starting with a single 1) of the Rule 150 cellular automaton on an infinite Bethe lattice with coordination number 3. Rule 150 sums the values of the focal node and its k neighbors, then applies modulo 2.

A323110 Aggregate values of n-th stage of growth for two-dimensional cellular automaton defined by "Rule 614", based on the 5-celled von Neumann neighborhood, calculated via even-zeroing instead of mod 2.

Original entry on oeis.org

1, 5, 9, 21, 9, 45, 57, 213, 129, 645, 1161, 2709, 657, 3285, 5841, 13869, 3129, 15645, 28161, 65709, 28161, 140805, 178353, 666477, 391137, 1955685, 3520233, 8213877, 3518721, 17593605, 22290273, 83271357, 48828129, 244140645, 439453161, 1025390709, 439453161, 2197265805, 2783203353, 10400391477
Offset: 0

Views

Author

Nathan M Epstein, Jan 04 2019

Keywords

Comments

It's helpful to define A072272 first: Consider only the four nearest (N,S,E,W) neighbors of a cell together with the cell itself. In the next state, the state of a cell will change if an odd number of these five cells is ON. This is equivalent to taking the sum of all 4 neighbor cells, together with the cell itself, mod 2. A072272 is the total number of active cells per generation. This sequence differs from A072272 because the state of the next cell can be any odd number instead of 1. Instead of applying mod 2 to the sum of the 5 local cells, this variation takes the sum of the 5 local cells, and then sets the value to zero if that value is even.
The generations of A072272 are congruent mod 2 to the generations of this automaton. A consequence of this is that the pattern of active cells is the same between both implementations of the CA. However, the values of the cells in this automaton differ from those in A072272. In this variation the values of cell are not constrained to the range [0,1]. The terms in this sequence are the aggregate values of all cells for each generation, instead of the number of cells.

Crossrefs

Cf. A072272.
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