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.

Previous Showing 11-20 of 21 results. Next

A325095 Number of subsets of {1...n} with no binary carries.

Original entry on oeis.org

1, 2, 4, 5, 10, 12, 14, 15, 30, 35, 40, 42, 47, 49, 51, 52, 104, 119, 134, 139, 154, 159, 164, 166, 181, 186, 191, 193, 198, 200, 202, 203, 406, 458, 510, 525, 577, 592, 607, 612, 664, 679, 694, 699, 714, 719, 724, 726, 778, 793, 808, 813, 828, 833, 838, 840
Offset: 0

Views

Author

Gus Wiseman, Mar 27 2019

Keywords

Comments

A binary carry of two positive integers is an overlap of the positions of 1's in their reversed binary expansion. For example, the binary representations of {2,5,8} are:
2 = 10,
5 = 101,
8 = 1000,
and since there are no columns with more than one 1, {2,5,8} is counted under a(8).

Examples

			The a(1) = 1 through a(7) = 15 subsets:
  {}   {}     {}     {}       {}       {}       {}
  {1}  {1}    {1}    {1}      {1}      {1}      {1}
       {2}    {2}    {2}      {2}      {2}      {2}
       {1,2}  {3}    {3}      {3}      {3}      {3}
              {1,2}  {4}      {4}      {4}      {4}
                     {1,2}    {5}      {5}      {5}
                     {1,4}    {1,2}    {6}      {6}
                     {2,4}    {1,4}    {1,2}    {7}
                     {3,4}    {2,4}    {1,4}    {1,2}
                     {1,2,4}  {2,5}    {1,6}    {1,4}
                              {3,4}    {2,4}    {1,6}
                              {1,2,4}  {2,5}    {2,4}
                                       {3,4}    {2,5}
                                       {1,2,4}  {3,4}
                                                {1,2,4}
		

Crossrefs

Programs

  • Maple
    b:= proc(n, t) option remember; `if`(n=0, 1, b(n-1, t)+
         `if`(Bits[And](n, t)=0, b(n-1, Bits[Or](n, t)), 0))
        end:
    a:= n-> b(n, 0):
    seq(a(n), n=0..63);  # Alois P. Heinz, Mar 28 2019
  • Mathematica
    binpos[n_]:=Join@@Position[Reverse[IntegerDigits[n,2]],1];
    stableQ[u_,Q_]:=!Apply[Or,Outer[#1=!=#2&&Q[#1,#2]&,u,u,1],{0,1}];
    Table[Length[Select[Subsets[Range[n]],stableQ[#,Intersection[binpos[#1],binpos[#2]]!={}&]&]],{n,0,10}]

Formula

a(2^n - 1) = A000110(n + 1).

Extensions

a(16)-a(55) from Alois P. Heinz, Mar 28 2019

A325109 Number of integer partitions of n whose distinct parts have no binary containments.

Original entry on oeis.org

1, 1, 2, 3, 4, 5, 8, 10, 12, 15, 18, 23, 28, 32, 41, 52, 57, 66, 76, 90, 99, 117, 131, 157, 172, 194, 216, 255, 276, 313, 358, 410, 447, 511, 546, 630, 677, 750, 818, 945, 990, 1108, 1200, 1338, 1429, 1606, 1713, 1928, 2062, 2263, 2412, 2725, 2847, 3142, 3389
Offset: 0

Views

Author

Gus Wiseman, Mar 28 2019

Keywords

Comments

A pair of positive integers is a binary containment if the positions of 1's in the reversed binary expansion of the first are a subset of the positions of 1's in the reversed binary expansion of the second.

Examples

			The a(1) = 1 through a(8) = 12 partitions:
  (1)  (2)   (3)    (4)     (5)      (6)       (7)        (8)
       (11)  (21)   (22)    (41)     (33)      (43)       (44)
             (111)  (211)   (221)    (42)      (52)       (53)
                    (1111)  (2111)   (222)     (61)       (422)
                            (11111)  (411)     (421)      (611)
                                     (2211)    (2221)     (2222)
                                     (21111)   (4111)     (4211)
                                     (111111)  (22111)    (22211)
                                               (211111)   (41111)
                                               (1111111)  (221111)
                                                          (2111111)
                                                          (11111111)
		

Crossrefs

Programs

  • Maple
    c:= proc() option remember; local i, x, y;
          x, y:= map(n-> Bits[Split](n), [args])[];
          for i to nops(x) do
            if x[i]=1 and y[i]=0 then return false fi
          od; true
        end:
    b:= proc(n, i, s) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1, s)+`if`(ormap(j-> c(i, j), s), 0, add(
          b(n-i*j, i-1, s union {i}), j=1..n/i))))
        end:
    a:= n-> b(n$2, {}):
    seq(a(n), n=0..55);  # Alois P. Heinz, Mar 29 2019
  • Mathematica
    binpos[n_]:=Join@@Position[Reverse[IntegerDigits[n,2]],1];
    stableQ[u_,Q_]:=!Apply[Or,Outer[#1=!=#2&&Q[#1,#2]&,u,u,1],{0,1}];
    Table[Length[Select[IntegerPartitions[n],stableQ[#,SubsetQ[binpos[#1],binpos[#2]]&]&]],{n,0,15}]
    (* Second program: *)
    c[args_List] := c[args] = Module[{i, x, y}, {x, y} = Reverse@IntegerDigits[#, 2]& /@ args; For[i = 1, i <= Length[x], i++, If[x[[i]] == 1 && y[[i]] == 0, Return[False]]]; True];
    b[n_, i_, s_List] := b[n, i, s] = If[n == 0, 1, If[i < 1, 0, b[n, i - 1, s] + If[AnyTrue[s, c[{i, #}]&], 0, Sum[b[n - i*j, i-1, s ~Union~ {i}], {j, 1, n/i}]]]];
    a[n_] := b[n, n, {}];
    a /@ Range[0, 55] (* Jean-François Alcover, Jun 03 2021, after Alois P. Heinz *)

Extensions

a(31)-a(54) from Alois P. Heinz, Mar 29 2019

A325101 Number of divisible binary-containment pairs of positive integers up to n.

Original entry on oeis.org

0, 1, 2, 4, 5, 7, 9, 11, 12, 14, 16, 18, 20, 22, 24, 28, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 53, 55, 57, 61, 63, 64, 66, 68, 70, 72, 74, 76, 79, 81, 83, 85, 87, 89, 93, 95, 97, 99, 101, 103, 107, 109, 111, 115, 118, 120, 122, 124, 126, 130, 132, 134
Offset: 0

Views

Author

Gus Wiseman, Mar 28 2019

Keywords

Comments

A pair of positive integers is divisible if the first divides the second, and is a binary containment if the positions of 1's in the reversed binary expansion of the first are a subset of those in the second.

Examples

			The a(1) = 1 through a(8) = 12 pairs:
  (1,1)  (1,1)  (1,1)  (1,1)  (1,1)  (1,1)  (1,1)  (1,1)
         (2,2)  (1,3)  (1,3)  (1,3)  (1,3)  (1,3)  (1,3)
                (2,2)  (2,2)  (1,5)  (1,5)  (1,5)  (1,5)
                (3,3)  (3,3)  (2,2)  (2,2)  (1,7)  (1,7)
                       (4,4)  (3,3)  (2,6)  (2,2)  (2,2)
                              (4,4)  (3,3)  (2,6)  (2,6)
                              (5,5)  (4,4)  (3,3)  (3,3)
                                     (5,5)  (4,4)  (4,4)
                                     (6,6)  (5,5)  (5,5)
                                            (6,6)  (6,6)
                                            (7,7)  (7,7)
                                                   (8,8)
		

Crossrefs

Programs

  • Mathematica
    Table[Length[Select[Tuples[Range[n],2],Divisible[#[[2]],#[[1]]]&&SubsetQ[Position[Reverse[IntegerDigits[#[[2]],2]],1],Position[Reverse[IntegerDigits[#1[[1]],2]],1]]&]],{n,0,30}]

Formula

a(n) = A325106(n) + n.

A325107 Number of subsets of {1...n} with no binary containments.

Original entry on oeis.org

1, 2, 4, 5, 10, 13, 18, 19, 38, 52, 77, 83, 133, 147, 166, 167, 334, 482, 764, 848, 1465, 1680, 1987, 2007, 3699, 4413, 5488, 5572, 7264, 7412, 7579, 7580, 15160, 22573, 37251, 42824, 77387, 92863, 116453, 118461, 227502, 286775, 382573, 392246, 555661, 574113
Offset: 0

Views

Author

Gus Wiseman, Mar 28 2019

Keywords

Comments

A pair of positive integers is a binary containment if the positions of 1's in the reversed binary expansion of the first are a subset of the positions of 1's in the reversed binary expansion of the second.

Examples

			The a(0) = 1 through a(6) = 18 subsets:
  {}  {}   {}     {}     {}       {}       {}
      {1}  {1}    {1}    {1}      {1}      {1}
           {2}    {2}    {2}      {2}      {2}
           {1,2}  {3}    {3}      {3}      {3}
                  {1,2}  {4}      {4}      {4}
                         {1,2}    {5}      {5}
                         {1,4}    {1,2}    {6}
                         {2,4}    {1,4}    {1,2}
                         {3,4}    {2,4}    {1,4}
                         {1,2,4}  {2,5}    {1,6}
                                  {3,4}    {2,4}
                                  {3,5}    {2,5}
                                  {1,2,4}  {3,4}
                                           {3,5}
                                           {3,6}
                                           {5,6}
                                           {1,2,4}
                                           {3,5,6}
		

Crossrefs

Programs

  • Maple
    c:= proc() option remember; local i, x, y;
          x, y:= map(n-> Bits[Split](n), [args])[];
          for i to nops(x) do
            if x[i]=1 and y[i]=0 then return false fi
          od; true
        end:
    b:= proc(n, s) option remember; `if`(n=0, 1, b(n-1, s)+
         `if`(ormap(i-> c(n, i), s), 0, b(n-1, s union {n})))
        end:
    a:= n-> b(n, {}):
    seq(a(n), n=0..34);  # Alois P. Heinz, Mar 28 2019
  • Mathematica
    binpos[n_]:=Join@@Position[Reverse[IntegerDigits[n,2]],1];
    stableQ[u_,Q_]:=!Apply[Or,Outer[#1=!=#2&&Q[#1,#2]&,u,u,1],{0,1}];
    Table[Length[Select[Subsets[Range[n]],stableQ[#,SubsetQ[binpos[#1],binpos[#2]]&]&]],{n,0,13}]

Formula

a(2^n - 1) = A014466(n).

Extensions

a(16)-a(45) from Alois P. Heinz, Mar 28 2019

A325108 Number of maximal subsets of {1...n} with no binary containments.

Original entry on oeis.org

1, 1, 1, 2, 2, 4, 5, 6, 6, 11, 13, 16, 17, 22, 27, 28
Offset: 0

Views

Author

Gus Wiseman, Mar 28 2019

Keywords

Comments

A pair of positive integers is a binary containment if the positions of 1's in the reversed binary expansion of the first are a subset of the positions of 1's in the reversed binary expansion of the second.

Examples

			The a(0) = 1 through a(7) = 6 maximal subsets:
  {}  {1}  {1,2}  {3}    {3,4}    {2,5}    {1,6}    {7}
                  {1,2}  {1,2,4}  {3,4}    {2,5}    {1,6}
                                  {3,5}    {3,4}    {2,5}
                                  {1,2,4}  {1,2,4}  {3,4}
                                           {3,5,6}  {1,2,4}
                                                    {3,5,6}
		

Crossrefs

Programs

  • Mathematica
    binpos[n_]:=Join@@Position[Reverse[IntegerDigits[n,2]],1];
    stableQ[u_,Q_]:=!Apply[Or,Outer[#1=!=#2&&Q[#1,#2]&,u,u,1],{0,1}];
    maxim[s_]:=Complement[s,Last/@Select[Tuples[s,2],UnsameQ@@#&&SubsetQ@@#&]];
    Table[Length[maxim[Select[Subsets[Range[n]],stableQ[#,SubsetQ[binpos[#1],binpos[#2]]&]&]]],{n,0,10}]

A325102 Number of ordered pairs of positive integers up to n with no binary carries.

Original entry on oeis.org

0, 0, 2, 2, 8, 10, 12, 12, 26, 32, 38, 40, 46, 48, 50, 50, 80, 94, 108, 114, 128, 134, 140, 142, 156, 162, 168, 170, 176, 178, 180, 180, 242, 272, 302, 316, 346, 360, 374, 380, 410, 424, 438, 444, 458, 464, 470, 472, 502, 516, 530, 536, 550, 556, 562, 564, 578
Offset: 0

Views

Author

Gus Wiseman, Mar 28 2019

Keywords

Comments

A binary carry of two positive integers is an overlap of the positions of 1's in their reversed binary expansion.

Examples

			The a(2) = 2 through a(6) = 12 pairs:
  (1,2)  (1,2)  (1,2)  (1,2)  (1,2)  (1,2)
  (2,1)  (2,1)  (1,4)  (1,4)  (1,4)  (1,4)
                (2,1)  (2,1)  (1,6)  (1,6)
                (2,4)  (2,4)  (2,1)  (2,1)
                (3,4)  (2,5)  (2,4)  (2,4)
                (4,1)  (3,4)  (2,5)  (2,5)
                (4,2)  (4,1)  (3,4)  (3,4)
                (4,3)  (4,2)  (4,1)  (4,1)
                       (4,3)  (4,2)  (4,2)
                       (5,2)  (4,3)  (4,3)
                              (5,2)  (5,2)
                              (6,1)  (6,1)
		

Crossrefs

Programs

  • Mathematica
    Table[Length[Select[Tuples[Range[n],2],Intersection[Position[Reverse[IntegerDigits[#[[1]],2]],1],Position[Reverse[IntegerDigits[#[[2]],2]],1]]=={}&]],{n,0,30}]

Formula

a(n) = 2 * A325103(n).

A325123 Number of divisible pairs of positive integers up to n with no binary carries.

Original entry on oeis.org

0, 0, 1, 1, 3, 3, 4, 4, 7, 7, 9, 9, 12, 12, 13, 13, 17, 17, 19, 19, 22, 22, 23, 23, 28, 28, 29, 29, 31, 31, 32, 32, 37, 37, 39, 39, 44, 44, 45, 45, 50, 50, 52, 52, 54, 54, 55, 55, 62, 62, 64, 64, 66, 66, 68, 68, 72, 72, 73, 73, 76, 76, 77, 77, 83, 83, 85, 85
Offset: 0

Views

Author

Gus Wiseman, Mar 29 2019

Keywords

Comments

Two positive integers are divisible if the first divides the second, and they have a binary carry if the positions of 1's in their reversed binary expansion overlap.
a(2k+1) = a(2k), since an odd number and any divisor will overlap in the last digit. Additionally, a(2k+2) > a(2k+1) because the pair {1,2k+2} is always valid. Therefore, every term appears exactly twice. - Charlie Neder, Apr 02 2019

Examples

			The a(2) = 1 through a(11) = 9 pairs:
  {1,2}  {1,2}  {1,2}  {1,2}  {1,2}  {1,2}  {1,2}  {1,2}  {1,2}   {1,2}
                {1,4}  {1,4}  {1,4}  {1,4}  {1,4}  {1,4}  {1,4}   {1,4}
                {2,4}  {2,4}  {1,6}  {1,6}  {1,6}  {1,6}  {1,6}   {1,6}
                              {2,4}  {2,4}  {1,8}  {1,8}  {1,8}   {1,8}
                                            {2,4}  {2,4}  {2,4}   {2,4}
                                            {2,8}  {2,8}  {2,8}   {2,8}
                                            {4,8}  {4,8}  {4,8}   {4,8}
                                                          {1,10}  {1,10}
                                                          {5,10}  {5,10}
		

Crossrefs

Programs

  • Mathematica
    Table[Length[Select[Tuples[Range[n],2],Divisible@@Reverse[#]&&Intersection[Position[Reverse[IntegerDigits[#[[1]],2]],1],Position[Reverse[IntegerDigits[#[[2]],2]],1]]=={}&]],{n,0,20}]

A325099 Number of binary carry-connected strict integer partitions of n.

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 3, 1, 4, 5, 8, 6, 11, 11, 15, 13, 18, 20, 30, 29, 43, 49, 68, 66, 84, 94, 125, 131, 165, 184, 237, 251, 291, 315, 383, 408, 486, 536, 663, 714, 832, 912, 1104, 1195, 1405, 1554, 1877, 2046, 2348, 2559, 2998, 3256, 3730, 4084, 4793, 5230, 5938
Offset: 0

Views

Author

Gus Wiseman, Mar 28 2019

Keywords

Comments

A binary carry of two positive integers is an overlap of the positions of 1's in their reversed binary expansion. An integer partition is binary carry-connected if the graph whose vertices are the parts and whose edges are binary carries is connected.

Examples

			The a(1) = 1 through a(11) = 6 strict partitions (A = 10, B = 11):
  (1)  (2)  (3)  (4)   (5)   (6)    (7)  (8)   (9)    (A)    (B)
                 (31)  (32)  (51)        (53)  (54)   (64)   (65)
                             (321)       (62)  (63)   (73)   (74)
                                         (71)  (72)   (91)   (632)
                                               (531)  (532)  (731)
                                                      (541)  (5321)
                                                      (631)
                                                      (721)
		

Crossrefs

Programs

  • Mathematica
    binpos[n_]:=Join@@Position[Reverse[IntegerDigits[n,2]],1];
    csm[s_]:=With[{c=Select[Tuples[Range[Length[s]],2],And[OrderedQ[#],UnsameQ@@#,Length[Intersection@@s[[#]]]>0]&]},If[c=={},s,csm[Sort[Append[Delete[s,List/@c[[1]]],Union@@s[[c[[1]]]]]]]]];
    Table[Length[Select[IntegerPartitions[n],UnsameQ@@#&&Length[csm[binpos/@#]]<=1&]],{n,0,30}]

A325100 Heinz numbers of strict integer partitions with no binary carries.

Original entry on oeis.org

1, 2, 3, 5, 6, 7, 11, 13, 14, 17, 19, 21, 23, 26, 29, 31, 33, 35, 37, 38, 41, 42, 43, 47, 53, 57, 58, 59, 61, 67, 69, 71, 73, 74, 79, 83, 86, 89, 95, 97, 101, 103, 106, 107, 109, 111, 113, 114, 122, 123, 127, 131, 133, 137, 139, 142, 149, 151, 157, 158, 159
Offset: 1

Views

Author

Gus Wiseman, Mar 28 2019

Keywords

Comments

A binary carry of two positive integers is an overlap of the positions of 1's in their reversed binary expansion.
The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1) * ... * prime(y_k), so these are squarefree numbers whose prime indices have no carries. A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.

Examples

			The sequence of terms together with their prime indices begins:
   1: {}
   2: {1}
   3: {2}
   5: {3}
   6: {1,2}
   7: {4}
  11: {5}
  13: {6}
  14: {1,4}
  17: {7}
  19: {8}
  21: {2,4}
  23: {9}
  26: {1,6}
  29: {10}
  31: {11}
  33: {2,5}
  35: {3,4}
  37: {12}
  38: {1,8}
  41: {13}
  42: {1,2,4}
		

Crossrefs

Programs

  • Mathematica
    binpos[n_]:=Join@@Position[Reverse[IntegerDigits[n,2]],1];
    stableQ[u_,Q_]:=!Apply[Or,Outer[#1=!=#2&&Q[#1,#2]&,u,u,1],{0,1}];
    Select[Range[100],SquareFreeQ[#]&&stableQ[PrimePi/@First/@FactorInteger[#],Intersection[binpos[#1],binpos[#2]]!={}&]&]

A325124 Number of divisible pairs of positive integers up to n with at least one binary carry.

Original entry on oeis.org

0, 1, 2, 4, 5, 7, 10, 12, 13, 16, 18, 20, 23, 25, 28, 32, 33, 35, 39, 41, 44, 48, 51, 53, 56, 59, 62, 66, 70, 72, 79, 81, 82, 86, 88, 92, 96, 98, 101, 105, 108, 110, 116, 118, 122, 128, 131, 133, 136, 139, 143, 147, 151, 153, 159, 163, 167, 171, 174, 176, 185
Offset: 0

Views

Author

Gus Wiseman, Mar 29 2019

Keywords

Comments

Two positive integers are divisible if the first divides the second, and they have a binary carry if the positions of 1's in their reversed binary expansion overlap.

Examples

			The a(1) = 1 through a(8) = 13 pairs:
  (1,1)  (1,1)  (1,1)  (1,1)  (1,1)  (1,1)  (1,1)  (1,1)
         (2,2)  (1,3)  (1,3)  (1,3)  (1,3)  (1,3)  (1,3)
                (2,2)  (2,2)  (1,5)  (1,5)  (1,5)  (1,5)
                (3,3)  (3,3)  (2,2)  (2,2)  (1,7)  (1,7)
                       (4,4)  (3,3)  (2,6)  (2,2)  (2,2)
                              (4,4)  (3,3)  (2,6)  (2,6)
                              (5,5)  (3,6)  (3,3)  (3,3)
                                     (4,4)  (3,6)  (3,6)
                                     (5,5)  (4,4)  (4,4)
                                     (6,6)  (5,5)  (5,5)
                                            (6,6)  (6,6)
                                            (7,7)  (7,7)
                                                   (8,8)
		

Crossrefs

Programs

  • Mathematica
    Table[Length[Select[Tuples[Range[n],2],Divisible@@Reverse[#]&&Intersection[Position[Reverse[IntegerDigits[#[[1]],2]],1],Position[Reverse[IntegerDigits[#[[2]],2]],1]]!={}&]],{n,0,20}]

Formula

a(n) = A307230(n) + n.
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