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 21 results. Next

A248907 Numbers consisting only of digits 2 and 3, ordered according to the value obtained when the digits are interspersed with (right-associative) ^ operators.

Original entry on oeis.org

2, 3, 22, 23, 32, 222, 33, 322, 223, 232, 323, 332, 2222, 3222, 233, 333, 2322, 3322, 2223, 3223, 2232, 3232, 2323, 3323, 2332, 3332, 22222, 32222, 23222, 33222, 2233, 3233, 2333, 3333, 22322, 32322, 23322, 33322, 22223, 32223, 23223, 33223, 22232, 32232
Offset: 1

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Author

Keywords

Comments

A256179(n) is found by treating the digits of a(n) as power towers. So for example, a(11) = 323, so A256179(11) = 6561 because 3^(2^3) = 6561. - Bob Selcoe, Mar 18 2015
This is a permutation of the list A032810 (numbers having only digits 2 and 3) in the sense that is a list with exactly the same terms but in different order, namely such that the ("power tower") function A256229 yields an increasing sequence. The permutation of the indices is given by A185969, cf. formula. - M. F. Hasler, Mar 21 2015

Crossrefs

For another version, see A299229 (each digit is a separate term).

Programs

  • Haskell
    a248907 = a032810 . a185969
    
  • Mathematica
    ClearAll[a, p];
    p[d_, n_] := d 10^IntegerLength[n] + n;
    a[n_ /; n <= 12] := a[n] = {2, 3, 22, 23, 32, 222, 33, 322, 223, 232, 323, 332}[[n]];
    a[n_ /; OddQ[n]]  := a[n] = p[2, a[(n - 1)/2]];
    a[n_] := a[n] = p[3, a[(n - 2)/2]];
    Array[a, 100]
  • PARI
    vecsort(A032810,(a,b)->A256229(a)>A256229(b)) \\ Assuming that A032810 is defined as a vector. Append [1..N] if the vector A032810 has too many (thus too large) elements: recall that 33333 => 3^(3^(3^(3^3))). - M. F. Hasler, Mar 21 2015

Formula

a(n) = A032810(A185969(n)).

Extensions

Edited by M. F. Hasler, Mar 21 2015

A299240 Ranks of {2,3}-power towers in which #2's > #3's; see Comments.

Original entry on oeis.org

1, 3, 6, 8, 9, 10, 13, 14, 17, 19, 21, 27, 28, 29, 30, 35, 36, 37, 39, 40, 41, 43, 44, 45, 47, 51, 55, 56, 57, 58, 59, 60, 61, 63, 71, 72, 73, 75, 79, 80, 81, 83, 87, 88, 89, 91, 95, 103, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124
Offset: 1

Views

Author

Clark Kimberling, Feb 07 2018

Keywords

Comments

Suppose that S is a set of real numbers. An S-power-tower, t, is a number t = x(1)^x(2)^...^x(k), where k >= 1 and x(i) is in S for i = 1..k. We represent t by (x(1), x(2), ..., x(k)), which for k > 1 is defined as (x(1), (x(2), ..., x(k))); (2,3,2) means 2^9. The number k is the *height* of t. If every element of S exceeds 1 and all the power towers are ranked in increasing order, the position of each in the resulting sequence is its *rank*. See A299229 for a guide to related sequences.
This sequence together with A299241 and A299242 partition the positive integers.

Examples

			The first six terms are the ranks of these towers: t(1) = (2), t(3) = (2,2), t(6) = (2,2,2), t(8) = (3,2,2), t(9) = (2,2,3), t(10) = (2,3,2).
		

Crossrefs

Programs

  • Mathematica
    t[1] = {2}; t[2] = {3}; t[3] = {2, 2}; t[4] = {2, 3}; t[5] = {3, 2};
    t[6] = {2, 2, 2}; t[7] = {3, 3}; t[8] = {3, 2, 2}; t[9] = {2, 2, 3};
    t[10] = {2, 3, 2}; t[11] = {3, 2, 3}; t[12] = {3, 3, 2};
    z = 190; g[k_] := If[EvenQ[k], {2}, {3}]; f = 6;
    While[f < 13, n = f; While[n < z, p = 1;
      While[p < 12, m = 2 n + 1; v = t[n]; k = 0;
        While[k < 2^p, t[m + k] = Join[g[k], t[n + Floor[k/2]]]; k = k + 1];
       p = p + 1; n = m]]; f = f + 1]
    Select[Range[1000], Count[t[#], 2] > Count[t[#], 3] &];   (* A299240 *)
    Select[Range[1000], Count[t[#], 2] == Count[t[#], 3] &];  (* A299241 *)
    Select[Range[1000], Count[t[#], 2] < Count[t[#], 3] &];   (* A299242 *)

A299241 Ranks of {2,3}-power towers in which #2's = #3's; see Comments.

Original entry on oeis.org

4, 5, 18, 20, 22, 23, 25, 31, 62, 74, 76, 77, 82, 84, 85, 90, 92, 93, 96, 97, 99, 104, 105, 107, 128, 129, 131, 135, 238, 246, 250, 252, 253, 294, 298, 300, 301, 306, 308, 309, 312, 313, 315, 326, 330, 332, 333, 338, 340, 341, 344, 345, 347, 358, 362, 364
Offset: 1

Views

Author

Clark Kimberling, Feb 07 2018

Keywords

Comments

Suppose that S is a set of real numbers. An S-power-tower, t, is a number t = x(1)^x(2)^...^x(k), where k >= 1 and x(i) is in S for i = 1..k. We represent t by (x(1), x(2), ..., x(k)), which for k > 1 is defined as (x(1), (x(2), ..., x(k))); (2,3,2) means 2^9. The number k is the *height* of t. If every element of S exceeds 1 and all the power towers are ranked in increasing order, the position of each in the resulting sequence is its *rank*. See A299229 for a guide to related sequences.
This sequence together with A299240 and A299242 partition the positive integers.

Examples

			The first six terms are the ranks of these towers: t(4) = (2,3), t(5) = (3,2), t(18) = (3,3,2,2), t(20) = (3,2,2,3), t(22) = (3,2,3,2), t(23) = (2,3,2,3).
		

Crossrefs

Programs

  • Mathematica
    t[1] = {2}; t[2] = {3}; t[3] = {2, 2}; t[4] = {2, 3}; t[5] = {3, 2};
    t[6] = {2, 2, 2}; t[7] = {3, 3}; t[8] = {3, 2, 2}; t[9] = {2, 2, 3};
    t[10] = {2, 3, 2}; t[11] = {3, 2, 3}; t[12] = {3, 3, 2};
    z = 190; g[k_] := If[EvenQ[k], {2}, {3}]; f = 6;
    While[f < 13, n = f; While[n < z, p = 1;
      While[p < 12, m = 2 n + 1; v = t[n]; k = 0;
        While[k < 2^p, t[m + k] = Join[g[k], t[n + Floor[k/2]]]; k = k + 1];
       p = p + 1; n = m]]; f = f + 1]
    Select[Range[1000], Count[t[#], 2] > Count[t[#], 3] &];   (* A299240 *)
    Select[Range[1000], Count[t[#], 2] == Count[t[#], 3] &]; (* this sequence *)
    Select[Range[1000], Count[t[#], 2] < Count[t[#], 3] &];   (* A299242 *)

A299242 Ranks of {2,3}-power towers in which #2's < #3's; see Comments.

Original entry on oeis.org

2, 7, 11, 12, 15, 16, 24, 26, 32, 33, 34, 38, 42, 46, 48, 49, 50, 52, 53, 54, 64, 65, 66, 67, 68, 69, 70, 78, 86, 94, 98, 100, 101, 102, 106, 108, 109, 110, 126, 130, 132, 133, 134, 136, 137, 138, 139, 140, 141, 142, 150, 154, 156, 157, 158, 166, 170, 172
Offset: 1

Views

Author

Clark Kimberling, Feb 07 2018

Keywords

Comments

Suppose that S is a set of real numbers. An S-power-tower, t, is a number t = x(1)^x(2)^...^x(k), where k >= 1 and x(i) is in S for i = 1..k. We represent t by (x(1), x(2), ..., x(k)), which for k > 1 is defined as (x(1), (x(2), ..., x(k))); (2,3,2) means 2^9. The number k is the *height* of t. If every element of S exceeds 1 and all the power towers are ranked in increasing order, the position of each in the resulting sequence is its *rank*. See A299229 for a guide to related sequences.
This sequence together with A299240 and A299241 partition the positive integers.

Examples

			The first six terms are the ranks of these towers: t(2) = (3), t(7) = (3,3), t(11) = (3,2,3), t(12) = (3,3,2), t(15) = (2,3,3), t(16) = (3,3,3).
		

Crossrefs

Programs

  • Mathematica
    t[1] = {2}; t[2] = {3}; t[3] = {2, 2}; t[4] = {2, 3}; t[5] = {3, 2};
    t[6] = {2, 2, 2}; t[7] = {3, 3}; t[8] = {3, 2, 2}; t[9] = {2, 2, 3};
    t[10] = {2, 3, 2}; t[11] = {3, 2, 3}; t[12] = {3, 3, 2};
    z = 190; g[k_] := If[EvenQ[k], {2}, {3}]; f = 6;
    While[f < 13, n = f; While[n < z, p = 1;
      While[p < 12, m = 2 n + 1; v = t[n]; k = 0;
        While[k < 2^p, t[m + k] = Join[g[k], t[n + Floor[k/2]]]; k = k + 1];
       p = p + 1; n = m]]; f = f + 1]
    Select[Range[1000], Count[t[#], 2] > Count[t[#], 3] &];   (* A299240 *)
    Select[Range[1000], Count[t[#], 2] == Count[t[#], 3] &];  (* A299241 *)
    Select[Range[1000], Count[t[#], 2] < Count[t[#], 3] &];  (* this sequence *)

A299231 Ranks of {2,3}-power towers that start with 2; see Comments.

Original entry on oeis.org

1, 3, 4, 6, 9, 10, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119, 121, 123, 125
Offset: 1

Views

Author

Clark Kimberling, Feb 06 2018

Keywords

Comments

Suppose that S is a set of real numbers. An S-power-tower, t, is a number t = x(1)^x(2)^...^x(k), where k >= 1 and x(i) is in S for i = 1..k. We represent t by (x(1), x(2), ..., x(k)), which for k > 1 is defined as (x(1), (x(2), ..., x(k))); (2,3,2) means 2^9. The number k is the *height* of t. If every element of S exceeds 1 and all the power towers are ranked in increasing order, the position of each in the resulting sequence is its *rank*. See A299229 for a guide to related sequences.

Examples

			t(97) = (2,3,2,3,2,3), so that 97 is in the sequence.
		

Crossrefs

Cf. A299229, A299232 (complement).

Programs

  • Mathematica
    t[1] = {2}; t[2] = {3}; t[3] = {2, 2}; t[4] = {2, 3}; t[5] = {3, 2};
    t[6] = {2, 2, 2}; t[7] = {3, 3}; t[8] = {3, 2, 2}; t[9] = {2, 2, 3};
    t[10] = {2, 3, 2}; t[11] = {3, 2, 3}; t[12] = {3, 3, 2};
    z = 190; g[k_] := If[EvenQ[k], {2}, {3}]; f = 6;
    While[f < 13, n = f; While[n < z, p = 1;
      While[p < 12, m = 2 n + 1; v = t[n]; k = 0;
        While[k < 2^p, t[m + k] = Join[g[k], t[n + Floor[k/2]]]; k = k + 1];
       p = p + 1; n = m]]; f = f + 1]
    Select[Range[200], First[t[#]] == 2 &]; (* A299231 *)
    Select[Range[200], First[t[#]] == 3 &]; (* A299232 *)

Formula

a(n) = 2n-1 for all n except 3, 4, and 6.

A299232 Ranks of {2,3}-power towers that start with 3; see Comments.

Original entry on oeis.org

2, 5, 7, 8, 11, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124
Offset: 1

Views

Author

Clark Kimberling, Feb 06 2018

Keywords

Comments

Suppose that S is a set of real numbers. An S-power-tower, t, is a number t = x(1)^x(2)^...^x(k), where k >= 1 and x(i) is in S for i = 1..k. We represent t by (x(1), x(2), ..., x(k)), which for k > 1 is defined as (x(1), (x(2), ..., x(k))); (2,3,2) means 2^9. The number k is the *height* of t. If every element of S exceeds 1 and all the power towers are ranked in increasing order, the position of each in the resulting sequence is its *rank*. See A299229 for a guide to related sequences.

Examples

			t(76) = (3,2,3,3,2,2), so that 76 is in the sequence.
		

Crossrefs

Cf. A299229, A299231 (complement).

Programs

  • Mathematica
    t[1] = {2}; t[2] = {3}; t[3] = {2, 2}; t[4] = {2, 3}; t[5] = {3, 2};
    t[6] = {2, 2, 2}; t[7] = {3, 3}; t[8] = {3, 2, 2}; t[9] = {2, 2, 3};
    t[10] = {2, 3, 2}; t[11] = {3, 2, 3}; t[12] = {3, 3, 2};
    z = 190; g[k_] := If[EvenQ[k], {2}, {3}]; f = 6;
    While[f < 13, n = f; While[n < z, p = 1;
      While[p < 12, m = 2 n + 1; v = t[n]; k = 0;
        While[k < 2^p, t[m + k] = Join[g[k], t[n + Floor[k/2]]]; k = k + 1];
       p = p + 1; n = m]]; f = f + 1]
    Select[Range[200], First[t[#]] == 2 &]; (* A299231 *)
    Select[Range[200], First[t[#]] == 3 &]; (* A299232 *)

Formula

a(n) = 2n for all n except 2, 3, and 5.

A299233 Ranks of {2,3}-power towers that end with 2; see Comments.

Original entry on oeis.org

1, 3, 5, 6, 8, 10, 12, 13, 14, 17, 18, 21, 22, 25, 26, 27, 28, 29, 30, 35, 36, 37, 38, 43, 44, 45, 46, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 71, 72, 73, 74, 75, 76, 77, 78, 87, 88, 89, 90, 91, 92, 93, 94, 103, 104, 105, 106, 107, 108, 109, 110, 111
Offset: 1

Views

Author

Clark Kimberling, Feb 06 2018

Keywords

Comments

Suppose that S is a set of real numbers. An S-power-tower, t, is a number t = x(1)^x(2)^...^x(k), where k >= 1 and x(i) is in S for i = 1..k. We represent t by (x(1), x(2), ..., x(k)), which for k > 1 is defined as (x(1), (x(2), ..., x(k))); (2,3,2) means 2^9. The number k is the *height* of t. If every element of S exceeds 1 and all the power towers are ranked in increasing order, the position of each in the resulting sequence is its *rank*. See A299229 for a guide to related sequences.

Examples

			t(76) = (3,2,3,3,2,2), so that 76 is in the sequence.
		

Crossrefs

Cf. A299229, A299234 (complement).

Programs

  • Mathematica
    t[1] = {2}; t[2] = {3}; t[3] = {2, 2}; t[4] = {2, 3}; t[5] = {3, 2};
    t[6] = {2, 2, 2}; t[7] = {3, 3}; t[8] = {3, 2, 2}; t[9] = {2, 2, 3};
    t[10] = {2, 3, 2}; t[11] = {3, 2, 3}; t[12] = {3, 3, 2};
    z = 190; g[k_] := If[EvenQ[k], {2}, {3}]; f = 6;
    While[f < 13, n = f; While[n < z, p = 1;
      While[p < 12, m = 2 n + 1; v = t[n]; k = 0;
        While[k < 2^p, t[m + k] = Join[g[k], t[n + Floor[k/2]]]; k = k + 1];
       p = p + 1; n = m]]; f = f + 1]
    Select[Range[200], Last[t[#]] == 2 &]; (* A299233 *)
    Select[Range[200], Last[t[#]] == 3 &]; (* A299234 *)

A299234 Ranks of {2,3}-power towers that end with 3; see Comments.

Original entry on oeis.org

2, 4, 7, 9, 11, 15, 16, 19, 20, 23, 24, 31, 32, 33, 34, 39, 40, 41, 42, 47, 48, 49, 50, 63, 64, 65, 66, 67, 68, 69, 70, 79, 80, 81, 82, 83, 84, 85, 86, 95, 96, 97, 98, 99, 100, 101, 102, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140
Offset: 1

Views

Author

Clark Kimberling, Feb 06 2018

Keywords

Comments

Suppose that S is a set of real numbers. An S-power-tower, t, is a number t = x(1)^x(2)^...^x(k), where k >= 1 and x(i) is in S for i = 1..k. We represent t by (x(1), x(2), ..., x(k)), which for k > 1 is defined as (x(1), (x(2), ..., x(k))); (2,3,2) means 2^9. The number k is the *height* of t. If every element of S exceeds 1 and all the power towers are ranked in increasing order, the position of each in the resulting sequence is its *rank*. See A299229 for a guide to related sequences.

Examples

			t(80) = (3,2,2,2,2,3), so that 80 is in the sequence.
		

Crossrefs

Cf. A299229, A299233 (complement).

Programs

  • Mathematica
    t[1] = {2}; t[2] = {3}; t[3] = {2, 2}; t[4] = {2, 3}; t[5] = {3, 2};
    t[6] = {2, 2, 2}; t[7] = {3, 3}; t[8] = {3, 2, 2}; t[9] = {2, 2, 3};
    t[10] = {2, 3, 2}; t[11] = {3, 2, 3}; t[12] = {3, 3, 2};
    z = 190; g[k_] := If[EvenQ[k], {2}, {3}]; f = 6;
    While[f < 13, n = f; While[n < z, p = 1;
      While[p < 12, m = 2 n + 1; v = t[n]; k = 0;
        While[k < 2^p, t[m + k] = Join[g[k], t[n + Floor[k/2]]]; k = k + 1];
       p = p + 1; n = m]]; f = f + 1]
    Select[Range[200], Last[t[#]] == 2 &]; (* A299233 *)
    Select[Range[200], Last[t[#]] == 3 &]; (* A299234 *)

A299235 Number of 2's in the n-th {2,3}-power tower; see Comments.

Original entry on oeis.org

1, 0, 2, 1, 1, 3, 0, 2, 2, 2, 1, 1, 4, 3, 1, 0, 3, 2, 3, 2, 3, 2, 2, 1, 2, 1, 5, 4, 4, 3, 2, 1, 1, 0, 4, 3, 3, 2, 4, 3, 3, 2, 4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 6, 5, 5, 4, 5, 4, 4, 3, 3, 2, 2, 1, 2, 1, 1, 0, 5, 4, 4, 3, 4, 3, 3, 2, 5, 4, 4, 3, 4, 3, 3, 2
Offset: 1

Views

Author

Clark Kimberling, Feb 06 2018

Keywords

Comments

Suppose that S is a set of real numbers. An S-power-tower, t, is a number t = x(1)^x(2)^...^x(k), where k >= 1 and x(i) is in S for i = 1..k. We represent t by (x(1), x(2), ..., x(k)), which for k > 1 is defined as (x(1), (x(2), ..., x(k))); (2,3,2) means 2^9. The number k is the *height* of t. If every element of S exceeds 1 and all the power towers are ranked in increasing order, the position of each in the resulting sequence is its *rank*. See A299229 for a guide to related sequences.
Every nonnegative integer occurs infinitely many times in the sequence. In particular, a(n) = 0 when the tower consists exclusively of 3's. The position of the n-th 0 in the sequence is the rank of the n-th {3}-power tower, given by 9*2^(n-2)-2 for n > 1.

Examples

			t(80) = (3,2,2,2,2,3), so that a(80) = 4.
		

Crossrefs

Cf. A299229, A299236 (complement).

Programs

  • Mathematica
    t[1] = {2}; t[2] = {3}; t[3] = {2, 2}; t[4] = {2, 3}; t[5] = {3, 2};
    t[6] = {2, 2, 2}; t[7] = {3, 3}; t[8] = {3, 2, 2}; t[9] = {2, 2, 3};
    t[10] = {2, 3, 2}; t[11] = {3, 2, 3}; t[12] = {3, 3, 2};
    z = 190; g[k_] := If[EvenQ[k], {2}, {3}]; f = 6;
    While[f < 13, n = f; While[n < z, p = 1;
      While[p < 12, m = 2 n + 1; v = t[n]; k = 0;
        While[k < 2^p, t[m + k] = Join[g[k], t[n + Floor[k/2]]]; k = k + 1];
       p = p + 1; n = m]]; f = f + 1]
    Table[Count[t[n], 2], {n, 1, 100}];  (* A299235 *)
    Table[Count[t[n], 3], {n, 1, 100}];  (* A299236 *)

A299236 Number of 3's in the n-th {2,3}-power tower; see Comments.

Original entry on oeis.org

0, 1, 0, 1, 1, 0, 2, 1, 1, 1, 2, 2, 0, 1, 2, 3, 1, 2, 1, 2, 1, 2, 2, 3, 2, 3, 0, 1, 1, 2, 2, 3, 3, 4, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 0, 1, 1, 2, 1, 2, 2, 3, 2, 3, 3, 4, 3, 4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3, 2, 3, 3, 4
Offset: 1

Views

Author

Clark Kimberling, Feb 06 2018

Keywords

Comments

Suppose that S is a set of real numbers. An S-power-tower, t, is a number t = x(1)^x(2)^...^x(k), where k >= 1 and x(i) is in S for i = 1..k. We represent t by (x(1), x(2), ..., x(k)), which for k > 1 is defined as (x(1), (x(2), ..., x(k))); (2,3,2) means 2^9. The number k is the *height* of t. If every element of S exceeds 1 and all the power towers are ranked in increasing order, the position of each in the resulting sequence is its *rank*. See A299229 for a guide to related sequences.
Every nonnegative integer occurs infinitely many times in the sequence. In particular, a(n) = 0 when the tower consists exclusively of 2's. The position of the n-th 0 in the sequence is the rank of the n-th {2}-power tower, given by 7*2^(n-3) - 1 for n > 2.

Examples

			t(13) = (2,2,2,2), so that a(13) = 0.
		

Crossrefs

Cf. A299229, A299235 (complement).

Programs

  • Mathematica
    t[1] = {2}; t[2] = {3}; t[3] = {2, 2}; t[4] = {2, 3}; t[5] = {3, 2};
    t[6] = {2, 2, 2}; t[7] = {3, 3}; t[8] = {3, 2, 2}; t[9] = {2, 2, 3};
    t[10] = {2, 3, 2}; t[11] = {3, 2, 3}; t[12] = {3, 3, 2};
    z = 190; g[k_] := If[EvenQ[k], {2}, {3}]; f = 6;
    While[f < 13, n = f; While[n < z, p = 1;
      While[p < 12, m = 2 n + 1; v = t[n]; k = 0;
        While[k < 2^p, t[m + k] = Join[g[k], t[n + Floor[k/2]]]; k = k + 1];
       p = p + 1; n = m]]; f = f + 1]
    Table[Count[t[n], 2], {n, 1, 100}];  (* A299235 *)
    Table[Count[t[n], 3], {n, 1, 100}];  (* A299236 *)
Showing 1-10 of 21 results. Next