A224809 -id:A224809 - cp's OEIS frontend

A376033 Number A(n,k) of binary words of length n avoiding distance (i+1) between "1" digits if the i-th bit is set in the binary representation of k; square array A(n,k), n>=0, k>=0, read by antidiagonals.

1, 1, 2, 1, 2, 4, 1, 2, 3, 8, 1, 2, 4, 5, 16, 1, 2, 3, 6, 8, 32, 1, 2, 4, 4, 9, 13, 64, 1, 2, 3, 8, 6, 15, 21, 128, 1, 2, 4, 5, 12, 9, 25, 34, 256, 1, 2, 3, 6, 7, 18, 13, 40, 55, 512, 1, 2, 4, 4, 8, 11, 27, 19, 64, 89, 1024, 1, 2, 3, 8, 5, 11, 16, 45, 28, 104, 144, 2048

Offset: 0

Alois P. Heinz, Sep 09 2024

Also the number of subsets of [n] avoiding distance (i+1) between elements if the i-th bit is set in the binary representation of k. A(6,3) = 13: {}, {1}, {2}, {3}, {4}, {5}, {6}, {1,4}, {1,5}, {1,6}, {2,5}, {2,6}, {3,6}.
Each column sequence satisfies a linear recurrence with constant coefficients.
The sequence of row n is periodic with period A011782(n) = ceiling(2^(n-1)).

			A(6,6) = 17: 000000, 000001, 000010, 000011, 000100, 000110, 001000, 001100, 010000, 010001, 011000, 100000, 100001, 100010, 100011, 110000, 110001 because 6 = 110_2 and no two "1" digits have distance 2 or 3.
A(6,7) = 10: 000000, 000001, 000010, 000100, 001000, 010000, 010001, 100000, 100001, 100010.
A(7,7) = 14: 0000000, 0000001, 0000010, 0000100, 0001000, 0010000, 0010001, 0100000, 0100001, 0100010, 1000000, 1000001, 1000010, 1000100.
Square array A(n,k) begins:
     1,  1,   1,  1,   1,  1,  1,  1,   1,  1, ...
     2,  2,   2,  2,   2,  2,  2,  2,   2,  2, ...
     4,  3,   4,  3,   4,  3,  4,  3,   4,  3, ...
     8,  5,   6,  4,   8,  5,  6,  4,   8,  5, ...
    16,  8,   9,  6,  12,  7,  8,  5,  16,  8, ...
    32, 13,  15,  9,  18, 11, 11,  7,  24, 11, ...
    64, 21,  25, 13,  27, 16, 17, 10,  36, 17, ...
   128, 34,  40, 19,  45, 25, 27, 14,  54, 25, ...
   256, 55,  64, 28,  75, 37, 41, 19,  81, 37, ...
   512, 89, 104, 41, 125, 57, 60, 26, 135, 57, ...

Alois P. Heinz, Antidiagonals n = 0..200, flattened

Columns k=0-20 give: A000079, A000045(n+2), A006498(n+2), A000930(n+2), A006500, A130137, A079972(n+3), A003269(n+4), A031923(n+1), A263710(n+1), A224809(n+4), A317669(n+4), A351873, A351874, A121832(n+4), A003520(n+4), A208742, A374737, A375977, A375980, A375978.
Rows n=0-2 give: A000012, A007395(k+1), A010702(k+1).
Main diagonal gives A376091.
A(n,2^k-1) gives A141539.
A(2^n-1,2^n-1) gives A376697.
A(n,2^k) gives A209435.
Cf. A011782, A062383, A098011, A376921.

h:= proc(n) option remember; `if`(n=0, 1, 2^(1+ilog2(n))) end:
b:= proc(n, k, t) option remember; `if`(n=0, 1, add(`if`(j=1 and
      Bits[And](t, k)>0, 0, b(n-1, k, irem(2*t+j, h(k)))), j=0..1))
    end:
A:= (n, k)-> b(n, k, 0):
seq(seq(A(n, d-n), n=0..d), d=0..12);

step(v,b)={vector(#v, i, my(j=(i-1)>>1); if(bittest(i-1,0), if(bitand(b,j)==0, v[1+j], 0), v[1+j] + v[1+#v/2+j]));}
col(n,k)={my(v=vector(2^(1+logint(k,2))), r=vector(1+n)); v[1]=r[1]=1; for(i=1, n, v=step(v,k); r[1+i]=vecsum(v)); r}
A(n,k)=if(k==0, 2^n, col(n,k)[n+1]) \\ Andrew Howroyd, Oct 03 2024

A(n,k) = A(n,k+ceiling(2^(n-1))).
A(n,ceiling(2^(n-1))-1) = n+1.
A(n,ceiling(2^(n-2))) = ceiling(3*2^(n-2)) = A098011(n+2).

A264520 T(n,k)=Number of (n+1)X(k+1) arrays of permutations of 0..(n+1)*(k+1)-1 with each element having directed index change -1,0 0,2 -1,-2 or 1,0.

Original entry on oeis.org

1, 1, 0, 1, 0, 1, 2, 1, 3, 0, 4, 2, 9, 0, 1, 6, 4, 42, 36, 12, 0, 9, 8, 196, 228, 144, 0, 1, 12, 16, 644, 1444, 1644, 576, 46, 0, 16, 32, 2116, 8018, 18769, 10368, 2116, 0, 1, 24, 64, 6854, 44521, 169195, 186624, 65182, 8281, 177, 0, 36, 128, 22201, 258264, 1525225

Offset: 1

R. H. Hardin, Nov 16 2015

Table starts
.1...1......1........2..........4............6..............9...............12
.0...0......1........2..........4............8.............16...............32
.1...3......9.......42........196..........644...........2116.............6854
.0...0.....36......228.......1444.........8018..........44521...........258264
.1..12....144.....1644......18769.......169195........1525225.........14158040
.0...0....576....10368.....186624......2856816.......43731769........696507612
.1..46...2116....65182....2007889.....50099452.....1250046736......33040712340
.0...0...8281...414414...20738916....868998834....36412654041....1611878726112
.1.177..31329..2603670..216384100..14882827790..1023636039001...75733369600339
.0...0.121801.16540506.2246191236.256959272592.29395568245824.3617985452054688

			Some solutions for n=4 k=4
..7..8..9..1..2....7..8..0..1..2....7..8..0..1..2....5..8..7..1..2
..0.13.14..3..4...10.11.14..3..4...10.11.12..3..4....0.13.14..3..4
..5..6.10.18.12....5..6.17.18..9....5..6.19.18..9...17..6.10.11..9
.20.11.22.23.24...22.23.12.13.24...20.23.24.13.14...22.21.12.23.24
.15.16.17.21.19...15.16.20.21.19...15.16.17.21.22...15.16.20.18.19

R. H. Hardin, Table of n, a(n) for n = 1..160

Row 1 is A224809(n+1).

Row 2 is A000079(n-3).

Empirical for column k:
k=1: a(n) = a(n-2)
k=2: a(n) = 6*a(n-2) -11*a(n-4) +13*a(n-6) -11*a(n-8) +6*a(n-10) -a(n-12)
k=3: [order 19]
k=4: [order 84]
k=5: [order 90]
Empirical for row n:
n=1: a(n) = a(n-1) +a(n-3) -a(n-4) +a(n-5) +a(n-6) -a(n-9)
n=2: a(n) = 2*a(n-1)

A354665 Triangle read by rows, T(n,k) = T(n-1,k) + T(n-1,k-1) - T(n-2,k-1) + T(n-2,k-2) + T(n-3,k-1) - T(n-3,k-3) + delta(n,0)delta(k,0) - delta(n,1)delta(k,1), T(n

Original entry on oeis.org

1, 1, 0, 1, 0, 1, 1, 1, 2, 0, 1, 2, 4, 0, 1, 1, 3, 6, 3, 3, 0, 1, 4, 9, 8, 9, 0, 1, 1, 5, 13, 17, 18, 6, 4, 0, 1, 6, 18, 30, 36, 20, 16, 0, 1, 1, 7, 24, 48, 66, 55, 40, 10, 5, 0, 1, 8, 31, 72, 114, 120, 100, 40, 25, 0, 1, 1, 9, 39, 103, 186

Offset: 0

Michael A. Allen, Jun 04 2022

This is the m=2, t=3 member of a two-parameter family of triangles such that T(n,k) is the number of tilings of an (n+(t-1)*k) X 1 board using k (1,m-1;t)-combs and n-k unit square tiles. A (1,g;t)-comb is composed of a line of t unit square tiles separated from each other by gaps of width g.
T(2*j+r-2*k,k) is the coefficient of x^k in (f(j,x))^(2-r)*(f(j+1,x))^r for  r=0,1, where f(n,x) is a Narayana's cows polynomial defined by f(n,x)=f(n-1,x)+x*f(n-3,x)+delta(n,0) where f(n<0,x)=0.
T(n+4-2*k,k) is the number of subsets of {1,2,...,n} of size k such that no two elements in a subset differ by 2 or 4.

			Triangle begins:
  1;
  1,   0;
  1,   0,   1;
  1,   1,   2,   0;
  1,   2,   4,   0,   1;
  1,   3,   6,   3,   3,   0;
  1,   4,   9,   8,   9,   0,   1;
  1,   5,  13,  17,  18,   6,   4,   0;
  1,   6,  18,  30,  36,  20,  16,   0,   1;
  1,   7,  24,  48,  66,  55,  40,  10,   5,   0;
  1,   8,  31,  72, 114, 120, 100,  40,  25,   0,   1;
  1,   9,  39, 103, 186, 234, 221, 135,  75,  15,   6,   0;
...

Michael A. Allen, On a Two-Parameter Family of Generalizations of Pascal's Triangle, arXiv:2209.01377 [math.CO], 2022.
Michael A. Allen, On A Two-Parameter Family of Generalizations of Pascal's Triangle, J. Int. Seq. 25 (2022) Article 22.9.8.

Row sums are A011782.
Sums over k of T(n-2*k,k) are A224809.
Other members of the family of triangles: A007318 (m=1,t=2), A059259 (m=2,t=2), A350110 (m=3,t=2), A350111 (m=4,t=2), A350112 (m=5,t=2), A354666 (m=2,t=4), A354667 (m=2,t=5), A354668 (m=3,t=3).
Other triangles related to tiling using combs: A059259, A123521, A157897, A335964.

Mathematica
```
T[n_, k_]:=If[k<0 || n
				
```

T(n,0) = 1.
T(n,n) = delta(n mod 2,0).
T(n,1) = n-2 for n>1.
T(2*j-r,2*j-1) = 0 for j>0, r=0,1.
T(2*(j-1)+p,2*(j-1)) = j^p for j>0 and p=0,1,2.
T(2*(j-1)+3,2*(j-1)) = j^2*(j+1)/2 for j>0.
T(2*j+p,2*j-p) = C(j+1,2)^p for j>0 and p=0,1,2.
G.f. of row sums: (1-x)/(1-2*x).
G.f. of sums of T(n-2*k,k) over k: (1-x^3)/((1-x-x^3)*(1+x^4-x^6)).
T(n,k) = T(n-1,k) + T(n-1,k-1) for n>=2*k+1 if k>=0.

A115422 Integers n > 0 such that n XOR 20n = 21n.

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 32, 33, 36, 48, 64, 65, 66, 67, 72, 73, 96, 97, 128, 129, 130, 131, 132, 134, 144, 146, 192, 193, 194, 195, 256, 257, 258, 259, 260, 262, 264, 265, 268, 288, 289, 292, 384, 385, 386, 387, 388, 390, 512, 513, 514, 515, 516, 518

Offset: 1

Paul D. Hanna, Jan 22 2006

nonn

n is in the sequence iff 2*n is in the sequence. - Robert Israel, Nov 11 2016

Ivan Neretin, Table of n, a(n) for n = 1..10203

Cf. A003714 (Fibbinary numbers), A048715, A048718, A115423, A115424.

select(n -> Bits:-Xor(n,20*n)=21*n, [$1..1000]); # Robert Israel, Nov 11 2016

Select[Range[600],BitXor[#,20#]==21#&] (* Harvey P. Dale, Apr 21 2018 *)

isok(n) = bitxor(n, 20*n) == 21*n; \\ Michel Marcus, Nov 11 2016

$cnt=0;
foreach(1..1_000){
    print ++$cnt," $\n" if ((20*$)^$)==21*$;
}
# Ivan Neretin, Nov 10 2016

This sequence also seems to satisfy:
5*a(n) XOR 16*a(n) = 21*a(n);
5*a(n) XOR 17*a(n) = 20*a(n); etc.
a(A224809(n+4)) = 2^n. - Gheorghe Coserea, Nov 11 2016

A376743 Number of permutations (p(1),p(2),...,p(n)) of (1,2,...,n) such that p(i)-i is in {-2,-1,4} for all i=1,...,n.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 5, 5, 6, 8, 11, 15, 25, 35, 46, 61, 85, 125, 175, 245, 341, 470, 650, 925, 1300, 1810, 2521, 3520, 4915, 6880, 9640, 13476, 18801, 26251, 36721, 51346, 71776, 100335, 140210, 195886, 273813, 382821, 535105, 747850, 1045220

Offset: 0

Michael A. Allen, Oct 03 2024

Other sequences related to strongly restricted permutations pi(i) of i in {1,..,n} along with the sets of allowed p(i)-i (containing at least 3 elements): A000045 {-1,0,1}, A189593 {-1,0,2,3,4,5,6}, A189600 {-1,0,2,3,4,5,6,7}, A006498 {-2,0,2}, A080013 {-2,1,2}, A080014 {-2,0,1,2}, A033305 {-2,-1,1,2}, A002524 {-2,-1,0,1,2}, A080000 {-2,0,3}, A080001 {-2,1,3}, A080004 {-2,0,1,3}, A080002 {-2,2,3}, A080005 {-2,0,2,3}, A080008 {-2,1,2,3}, A080011 {-2,0,1,2,3}, A079999 {-2,-1,3}, A080003 {-2,-1,0,3}, A080006 {-2,-1,1,3}, A080009 {-2,-1,0,1,3}, A080007 {-2,-1,2,3}, A080010 {-2,-1,0,2,3}, A080012 {-2,-1,1,2,3}, A072827 {-2,-1,0,1,2,3}, A224809 {-2,0,4}, A189585 {-2,0,1,3,4}, A189581 {-2,-1,0,3,4}, A072850 {-2,-1,0,1,2,3,4}, A189587 {-2,0,1,3,4,5}, A189588 {-2,-1,0,3,4,5}, A189594 {-2,0,1,3,4,5,6}, A189595 {-2,-1,0,3,4,5,6}, A189601 {-2,0,1,3,4,5,6,7}, A189602 {-2,-1,0,3,4,5,6,7}, A224811 {-2,0,8}, A224812 {-2,0,10}, A224813 {-2,0,12}, A006500 {-3,0,3}, A079981 {-3,1,3}, A079983 {-3,0,1,3}, A079982 {-3,2,3}, A079984 {-3,0,2,3}, A079988 {-3,1,2,3}, A079989 {-3,0,1,2,3}, A079986 {-3,-1,1,3}, A079992 {-3,-1,0,1,3}, A079987 {-3,-1,2,3}, A079990 {-3,-1,0,2,3}, A079993 {-3,-1,1,2,3}, A079985 {-3,-2,2,3}, A079991 {-3,-2,0,2,3}, A079996 {-3,-2,0,1,2,3}, A079994 {-3,-2,1,2,3}, A079997 {-3,-2, -1,1,2,3}, A002526 {-3,-2,-1,0,1,2,3}, A189586 {-3,0,1,2,4}, A189583 {-3,-1,0,2,4}, A189582 {-3,-2,0,1,4}, A189584 {-3,-2,-1,0,4}, A189589 {-3,0,1,2,4,5}, A189590 {-3,-1,0,2,4,5}, A189591 {-3,-2,1,4,5}, A189592 {-3,-2,-1,0,4,5}, A224810 {-3,0,6}, A189596 {-3,0,1,2,4,5,6}, A189597 {-3,-1,0,2,4,5,6}, A189598 {-3,-2,0,1,4,5,6}, A189599 {-3,-2,-1,0,4,5,6}, A224814 {-3,0,9}, A031923 {-4,0,4}, A072856 {-4,-3, -2,-1,0,1,2,3,4}, A224815 {-4,0,8}, A154654 {-5,-4,-3,-2,-1,0,1,2,3,4,5}, A154655 {-6,-5,-4,-3, -2,-1,0,1,2,3,4,5,6}.

[Keyword "less", because this comment should be moved to the Index to the OEIS, it is not appropriate here. - N. J. A. Sloane, Oct 25 2024]

D. H. Lehmer, Permutations with strongly restricted displacements. Combinatorial theory and its applications, II (Proc. Colloq., Balatonfured, 1969), North-Holland, Amsterdam, 1970, pp. 755-770.

Michael A. Allen and Kenneth Edwards, Connections between two classes of generalized Fibonacci numbers squared and permanents of (0,1) Toeplitz matrices, Lin. Multilin. Alg. 72:13 (2024) 2091-2103.
Vladimir Baltic, On the number of certain types of strongly restricted permutations, Applicable Analysis and Discrete Mathematics, 4(1) (2010), 119-135.
Kenneth Edwards and Michael A. Allen, Strongly restricted permutations and tiling with fences, Discrete Applied Mathematics, 187 (2015), 82-90.
Index entries for linear recurrences with constant coefficients, signature (0,0,1,1,1,2,1,0,-2,-2,0,-1,0,0,1).

See comments for other sequences related to strongly restricted permutations.

CoefficientList[Series[(1 - x^3 - x^4 - x^6 + x^9)/(1 - x^3 - x^4 - x^5 - 2*x^6 - x^7 + 2*x^9 + 2*x^10 + x^12 - x^15),{x,0,49}],x]
LinearRecurrence[{0, 0, 1, 1, 1, 2, 1, 0, -2, -2, 0, -1, 0, 0, 1}, {1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 5, 5, 6, 8}, 50]

a(n) = a(n-3) + a(n-4) + a(n-5) + 2*a(n-6) + a(n-7) - 2*a(n-9) - 2*a(n-10) - a(n-12) + a(n-15).

G.f.: (1 - x^3 - x^4 - x^6 + x^9)/(1 - x^3 - x^4 - x^5 - 2*x^6 - x^7 + 2*x^9 + 2*x^10 + x^12 - x^15).

A387020 Number of permutations (p(1),p(2),...,p(n)) of (1,2,...,n) such that p(i)-i is in {-2,0,5} for all i=1,...,n.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 3, 5, 7, 10, 13, 16, 20, 25, 34, 46, 67, 94, 130, 175, 231, 305, 400, 540, 729, 999, 1363, 1855, 2510, 3370, 4531, 6070, 8180, 11026, 14921, 20197, 27322, 36940, 49820, 67204, 90528, 122091, 164686, 222344, 300316, 405574, 547768, 739291, 997794, 1346130

Offset: 0

Michael A. Allen, Aug 13 2025

			a(7) = 2: 1234567, 6712345.
a(8) = 3: 12345678, 17823456, 67123458.

D. H. Lehmer, Permutations with strongly restricted displacements. Combinatorial theory and its applications, II (Proc. Colloq., Balatonfured, 1969), North-Holland, Amsterdam, 1970, pp. 755-770.

Vladimir Baltić, On the number of certain types of strongly restricted permutations, Applicable Analysis and Discrete Mathematics, 4(1) (2010), 119-135.
Kenneth Edwards and Michael A. Allen, Strongly restricted permutations and tiling with fences, Discrete Applied Mathematics, 187 (2015), 82-90.
Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,3,-2,2,-1,1,0,0,-3,1,-2,0,0,0,0,1).

Sequences for numbers of permutations such that p(i)-i is in {-2,0,d} for d=1,..,8: A000930, A006498, A080000, A224809, A387020, A224808, A387021, A224811.

CoefficientList[Series[(1 - 2*x^7 - x^9 + x^14)/(1 - x - 3*x^7 + 2*x^8 - 2*x^9 + x^10 - x^11 + 3*x^14 - x^15 + 2*x^16 - x^21),{x,0,51}],x]
LinearRecurrence[{1, 0, 0, 0, 0, 0, 3, -2, 2, -1, 1, 0, 0, -3, 1, -2, 0, 0, 0, 0, 1}, {1, 1, 1, 1, 1, 1, 1, 2, 3, 5, 7, 10, 13, 16, 20, 25, 34, 46, 67, 94, 130}, 52]

a(n) = a(n-1) + 3*a(n-7) - 2*a(n-8) + 2*a(n-9) - a(n-10) + a(n-11) - 3*a(n-14) + a(n-15) - 2*a(n-16) + a(n-21) for n >= 21.

G.f.: (1 - 2*x^7 - x^9 + x^14)/((1 - x)*(1 - x + x^2 - 2*x^3 + x^4 - x^5 - x^7 + x^10)*(1 + x + x^3 + 2*x^4 + x^5 + 2*x^6 + 2*x^7 + x^8 + x^9 + x^10)).

A387021 Number of permutations (p(1),p(2),...,p(n)) of (1,2,...,n) such that p(i)-i is in {-2,0,7} for all i=1,...,n.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 5, 7, 10, 13, 17, 21, 25, 30, 36, 46, 59, 81, 109, 153, 207, 277, 361, 463, 589, 743, 949, 1211, 1589, 2083, 2773, 3670, 4861, 6388, 8344, 10848, 14019, 18166, 23479, 30556, 39762, 52049, 68125, 89345, 117034, 153078, 199979, 260572, 339546, 441669, 575341

Offset: 0

Michael A. Allen, Aug 13 2025

			a(9)=2: 123456789, 891234567.

D. H. Lehmer, Permutations with strongly restricted displacements. Combinatorial theory and its applications, II (Proc. Colloq., Balatonfured, 1969), North-Holland, Amsterdam, 1970, pp. 755-770.

V. Baltic, On the number of certain types of strongly restricted permutations, Applicable Analysis and Discrete Mathematics, 4(1) (2010), 119-135.
Kenneth Edwards and Michael A. Allen, Strongly restricted permutations and tiling with fences, Discrete Applied Mathematics, 187 (2015), 82-90.
Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,0,0,4,-3,3,-2,2,-1,1,0,0,-6,3,-6,2,-3,0,0,0,0,4,-1,3,0,0,0,0,0,0,-1).

Sequences for numbers of permutations such that p(i)-i is in {-2,0,d} for d=1,...,8: A000930, A006498, A080000, A224809, A387020, A224808, A387021, A224811.

CoefficientList[Series[(1 - 3*x^9 - 2*x^11 - x^13 + 3*x^18 + 2*x^20 - x^27)/ (1 - x - 4*x^9 + 3*x^10 - 3*x^11 + 2*x^12 - 2*x^13 + x^14 - x^15 + 6*x^18 - 3*x^19 + 6*x^20 - 2*x^21 + 3*x^22 - 4*x^27 + x^28 - 3*x^29 + x^36),{x,0,55}],x]
LinearRecurrence[{1, 0, 0, 0, 0, 0, 0, 0, 4, -3, 3, -2, 2, -1, 1, 0, 0, -6, 3, -6, 2, -3, 0, 0, 0, 0, 4, -1, 3, 0, 0, 0, 0, 0, 0, -1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 5, 7, 10, 13, 17, 21, 25, 30, 36, 46, 59, 81, 109, 153, 207, 277, 361, 463, 589, 743, 949, 1211, 1589, 2083, 2773}, 56]

a(n) = a(n-1) + 4*a(n-9) - 3*a(n-10) + 3*a(n-11) - 2*a(n-12) + 2*a(n-13) - a(n-14) + a(n-15) - 6*a(n-18) + 3*a(n-19) - 6*a(n-20) + 2*a(n-21) - 3*a(n-22) + 4*a(n-27) - a(n-28) + 3*a(n-29) - a(n-36) for n >= 36.

G.f.: (1 - 3*x^9 - 2*x^11 - x^13 + 3*x^18 + 2*x^20 - x^27)/ (1 - x - 4*x^9 + 3*x^10 - 3*x^11 + 2*x^12 - 2*x^13 + x^14 - x^15 + 6*x^18 - 3*x^19 + 6*x^20 - 2*x^21 + 3*x^22 - 4*x^27 + x^28 - 3*x^29 + x^36).

cp's OEIS Frontend

A376033 Number A(n,k) of binary words of length n avoiding distance (i+1) between "1" digits if the i-th bit is set in the binary representation of k; square array A(n,k), n>=0, k>=0, read by antidiagonals.

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A264520 T(n,k)=Number of (n+1)X(k+1) arrays of permutations of 0..(n+1)*(k+1)-1 with each element having directed index change -1,0 0,2 -1,-2 or 1,0.

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A354665 Triangle read by rows, T(n,k) = T(n-1,k) + T(n-1,k-1) - T(n-2,k-1) + T(n-2,k-2) + T(n-3,k-1) - T(n-3,k-3) + delta(n,0)*delta(k,0) - delta(n,1)*delta(k,1), T(n

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A115422 Integers n > 0 such that n XOR 20*n = 21*n.

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A376743 Number of permutations (p(1),p(2),...,p(n)) of (1,2,...,n) such that p(i)-i is in {-2,-1,4} for all i=1,...,n.

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A387020 Number of permutations (p(1),p(2),...,p(n)) of (1,2,...,n) such that p(i)-i is in {-2,0,5} for all i=1,...,n.

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A387021 Number of permutations (p(1),p(2),...,p(n)) of (1,2,...,n) such that p(i)-i is in {-2,0,7} for all i=1,...,n.

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A354665 Triangle read by rows, T(n,k) = T(n-1,k) + T(n-1,k-1) - T(n-2,k-1) + T(n-2,k-2) + T(n-3,k-1) - T(n-3,k-3) + delta(n,0)delta(k,0) - delta(n,1)delta(k,1), T(n

A115422 Integers n > 0 such that n XOR 20n = 21n.