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 30 results. Next

A348571 In Zeckendorf representation: integers that set a new record for the number of Reverse and Add steps (A349239) needed to reach a palindrome (A094202).

Original entry on oeis.org

0, 2, 7, 20, 54, 63, 114, 1002, 1413, 3007, 4447, 35131, 599185, 2189416, 2738842, 3253273, 108250112
Offset: 1

Views

Author

A.H.M. Smeets, Oct 23 2021

Keywords

Comments

Corresponding record values in A348572.
For Zeckendorf representation of numbers see A014417.
Lychrel numbers, as given in A348570, are excluded from this list because it is believed that those numbers never reach a palindrome.

Examples

			Trajectory of 20, i.e., 101010 in Zeckendorf representation:
       101010 + 010101      =      1010100
      1010100 + 0010101     =     10010010
     10010010 + 01001001    =    100100100
    100100100 + 001001001   =   1000010001
   1000010001 + 1000100001  =  10100000010
  10100000010 + 01000000101 = 100100001001, which is palindromic.
Due to the fact that any number smaller than 20 reaches a palindrome in fewer than 6 steps, 20 is a record-setting nonnegative integer.
The Lychrel numbers, as given in A348570, are excluded, because it is believed that those numbers never reach a palindromic number.
		

Crossrefs

Cf. A014417 (Zeckendorf digits), A349239 (reverse and add), A094202 (palindromes).
Cf. A348572 (number of steps), A348570 (Lychrels).

A331191 Numbers whose dual Zeckendorf representations (A104326) are palindromic.

Original entry on oeis.org

0, 1, 3, 4, 6, 11, 12, 16, 19, 22, 32, 33, 38, 42, 48, 53, 64, 71, 87, 88, 98, 106, 110, 118, 124, 134, 142, 148, 174, 194, 205, 231, 232, 245, 255, 271, 284, 288, 304, 317, 323, 336, 346, 362, 375, 402, 420, 462, 474, 516, 548, 566, 608, 609, 635, 656, 666, 687
Offset: 1

Views

Author

Amiram Eldar, Jan 11 2020

Keywords

Comments

Pairs of numbers of the form {F(2*k-1)-2, F(2*k-1)-1}, for k >= 2, where F(k) is the k-th Fibonacci number, are consecutive terms in this sequence: {0, 1}, {3, 4}, {11, 12}, {32, 33}, ... - Amiram Eldar, Sep 03 2022

Examples

			4 is a term since its dual Zeckendorf representation, 101, is palindromic.
		

Crossrefs

Programs

  • Mathematica
    mirror[dig_, s_] := Join[dig, s, Reverse[dig]];
    select[v_, mid_] := Select[v, Length[#] == 0 || Last[#] != mid &];
    fib[dig_] := Plus @@ (dig * Fibonacci[Range[2, Length[dig] + 1]]);
    pals = Join[{{}}, Rest[Select[IntegerDigits[Range[0, 2^6 - 1], 2], SequenceCount[#, {0, 0}] == 0 &]]];
    Union@Join[{0}, fib /@ Join[mirror[#, {}] & /@ (select[pals, 0]), mirror[#, {0}] & /@ (select[pals, 0]), mirror[#, {1}] & /@ pals]]

A351712 Numbers whose minimal (or greedy) Lucas representation (A130310) is palindromic.

Original entry on oeis.org

0, 2, 6, 9, 13, 20, 24, 31, 49, 56, 64, 78, 100, 125, 136, 150, 158, 169, 201, 237, 252, 324, 342, 364, 378, 396, 404, 422, 444, 523, 581, 606, 650, 708, 845, 874, 910, 932, 961, 975, 1004, 1040, 1048, 1077, 1113, 1135, 1164, 1366, 1460, 1500, 1572, 1666, 1692, 1786
Offset: 1

Views

Author

Amiram Eldar, Feb 17 2022

Keywords

Comments

A000211(n) = Lucas(n) + 2 is a term for all n > 2, since the representation of Lucas(n) + 2 is 10...01 with n-1 0's between the two 1's.

Examples

			The first 10 terms are:
   n  a(n) A130310(a(n))
   ---------------------
   1   0               0
   2   2               1
   3   6            1001
   4   9           10001
   5  13          100001
   6  20         1000001
   7  24         1001001
   8  31        10000001
   9  49       100000001
  10  56       100010001
		

Crossrefs

Subsequence of A054770.
Similar sequences: A002113, A006995, A014190, A094202, A331191, A351717.

Programs

  • Mathematica
    lucasPalQ[n_] := Module[{s = {}, m = n, k = 1}, While[m > 0, If[m == 1, k = 1; AppendTo[s, k]; m = 0, If[m == 2, k = 0; AppendTo[s, k]; m = 0, While[LucasL[k] <= m, k++]; k--; AppendTo[s, k]; m -= LucasL[k]; k = 1]]]; PalindromeQ[IntegerDigits[Total[2^s], 2]]]; Select[Range[0, 2000], lucasPalQ]

A351717 Numbers whose maximal (or lazy) Lucas representation (A130311) is palindromic.

Original entry on oeis.org

0, 2, 3, 5, 6, 10, 12, 14, 17, 20, 28, 30, 34, 36, 42, 46, 56, 61, 75, 77, 85, 92, 94, 101, 107, 115, 122, 128, 150, 166, 176, 198, 200, 211, 219, 233, 244, 246, 260, 271, 277, 288, 296, 310, 321, 345, 360, 396, 405, 441, 469, 484, 520, 522, 544, 562, 570, 588
Offset: 1

Views

Author

Amiram Eldar, Feb 17 2022

Keywords

Comments

A001610(n) = Lucas(n+1) - 1 is a term for all n, since A001610(0) = 0 has the representation 0 and the representation of Lucas(n+1) - 1 is n 1's for n > 0.

Examples

			The first 10 terms are:
   n  a(n)  A130311(a(n))
   ----------------------
   1   0               0
   2   2               1
   3   3              11
   4   5             101
   5   6             111
   6  10            1111
   7  12           10101
   8  14           11011
   9  17           11111
  10  20          101101
		

Crossrefs

Programs

  • Mathematica
    lazy = Select[IntegerDigits[Range[6000], 2], SequenceCount[#, {0, 0}] == 0 &]; t = Total[# * Reverse @ LucasL[Range[0, Length[#] - 1]]] & /@ lazy; s = FromDigits /@ lazy[[TakeWhile[Flatten[FirstPosition[t, #] & /@ Range[Max[t]]], NumberQ]]]; Join[{0}, Position[s, _?PalindromeQ] // Flatten]

A352087 Numbers whose minimal (or greedy) tribonacci representation (A278038) is palindromic.

Original entry on oeis.org

0, 1, 3, 5, 8, 14, 18, 23, 25, 36, 40, 45, 52, 62, 71, 78, 82, 102, 110, 128, 148, 150, 163, 181, 198, 211, 229, 233, 246, 264, 275, 312, 326, 360, 397, 411, 426, 463, 477, 505, 529, 562, 593, 617, 650, 658, 682, 715, 746, 770, 781, 805, 838, 869, 893, 926, 928
Offset: 1

Views

Author

Amiram Eldar, Mar 04 2022

Keywords

Comments

A000073(n) + 1 is a term for n>=4, since its minimal tribonacci representation is 10...01 with n-4 0's between the two 1's.

Examples

			The first 10 terms are:
   n  a(n)  A278038(a(n))
  -----------------------
   1   0                0
   2   1                1
   3   3               11
   4   5              101
   5   8             1001
   6  14            10001
   7  18            10101
   8  23            11011
   9  25           100001
  10  36           101101
		

Crossrefs

Programs

  • Mathematica
    t[1] = 1; t[2] = 2; t[3] = 4; t[n_] := t[n] = t[n - 1] + t[n - 2] + t[n - 3]; q[n_] := Module[{s = {}, m = n, k}, While[m > 0, k = 1; While[t[k] <= m, k++]; k--; AppendTo[s, k]; m -= t[k]; k = 1]; PalindromeQ[FromDigits @ IntegerDigits[Total[2^(s - 1)], 2]]]; Select[Range[0, 1000], q]

A352105 Numbers whose maximal tribonacci representation (A352103) is palindromic.

Original entry on oeis.org

0, 1, 3, 5, 7, 8, 14, 18, 23, 27, 36, 40, 51, 52, 62, 69, 78, 88, 95, 102, 110, 130, 148, 156, 176, 181, 194, 211, 229, 242, 246, 264, 277, 294, 312, 325, 326, 363, 397, 411, 448, 463, 477, 514, 548, 562, 599, 617, 650, 674, 682, 715, 739, 770, 803, 827, 838, 862
Offset: 1

Views

Author

Amiram Eldar, Mar 05 2022

Keywords

Comments

A027084(n) is a term since its maximal tribonacci representation is n-1 1's and no 0's.
The pairs {A008937(3*k+1)-1, A008937(3*k+1)} = {0, 1}, {7, 8}, {51, 52}, ... are consecutive terms in this sequence: the maximal tribonacci representation of A008937(3*k+1)-1 is 3*k 1's and no 0's (except for k=0 where the representation is 0), and the maximal tribonacci representation of A008937(3*k+1) is of the form 100100...1001 with k blocks of 100 followed by a 1 at the end.

Examples

			The first 10 terms are:
   n  a(n)  A352103(a(n))
  --  ----  -------------
   1    0               0
   2    1               1
   3    3              11
   4    5             101
   5    7             111
   6    8            1001
   7   14            1111
   8   18           10101
   9   23           11011
  10   27           11111
		

Crossrefs

A027084 is a subsequence.

Programs

  • Mathematica
    t[1] = 1; t[2] = 2; t[3] = 4; t[n_] := t[n] = t[n - 1] + t[n - 2] + t[n - 3]; trib[n_] := Module[{s = {}, m = n, k}, While[m > 0, k = 1; While[t[k] <= m, k++]; k--; AppendTo[s, k]; m -= t[k]; k = 1]; IntegerDigits[Total[2^(s - 1)], 2]]; q[n_] := Module[{v = trib[n]}, nv = Length[v]; i = 1; While[i <= nv - 3, If[v[[i ;; i + 3]] == {1, 0, 0, 0}, v[[i ;; i + 3]] = {0, 1, 1, 1}; If[i > 3, i -= 4]]; i++]; i = Position[v, _?(# > 0 &)]; If[i == {}, True, PalindromeQ[FromDigits[v[[i[[1, 1]] ;; -1]]]]]]; Select[Range[0, 1000], q]

A095309 Numbers such that both their binary and Zeckendorf representations are palindromic.

Original entry on oeis.org

0, 1, 3, 9, 27, 33, 51, 127, 1755, 2805, 10437, 71377, 547233, 1007727, 2924109, 3358515, 3460299, 59768775, 977921175, 1022225871, 1769996491, 5606742245, 13759209651, 15569747991, 120793923335, 426202820195, 6287935078637, 21296868044633, 25068131362413
Offset: 1

Views

Author

Robert G. Wilson v, Jun 01 2004

Keywords

Crossrefs

Intersection of A006995 and A094202.

Programs

  • Mathematica
    fbz[n_] := Block[{k = Floor[ Log[ GoldenRatio, n*Sqrt[5]]], t = n, a = {}}, While[k > 1, If[Fibonacci[k] <= t, t = t - Fibonacci[k]; AppendTo[a, 1], AppendTo[a, 0]]; k-- ]; a]; Do[b = IntegerDigits[2n + 1, 2]; If[b == Reverse[b], f = fbz[2n + 1]; If[f == Reverse[f], Print[2n + 1]]], {n, 0, 10^9}]

Extensions

a(22)-a(29) from Chai Wah Wu, Jun 14 2018
a(1) = 0 added by Amiram Eldar, Jan 11 2020

A331891 Negabinary palindromes: nonnegative numbers whose negabinary expansion (A039724) is palindromic.

Original entry on oeis.org

0, 1, 3, 5, 7, 11, 17, 21, 23, 31, 43, 51, 57, 65, 77, 85, 87, 103, 127, 143, 155, 171, 195, 211, 217, 233, 257, 273, 285, 301, 325, 341, 343, 375, 423, 455, 479, 511, 559, 591, 603, 635, 683, 715, 739, 771, 819, 851, 857, 889, 937, 969, 993, 1025, 1073, 1105, 1117
Offset: 1

Views

Author

Amiram Eldar, Jan 30 2020

Keywords

Comments

Numbers of the form 2^(2*m-1) - 1 (A083420) and 2^(2*m) + 1 (A052539) are terms.

Examples

			5 is a term since its negabinary representation is 101 which is palindromic.
		

Crossrefs

Programs

  • Mathematica
    negabin[n_] := negabin[n] = If[n==0, 0, negabin[Quotient[n-1, -2]]*10 + Mod[n, 2]]; Select[Range[0, 1200], PalindromeQ @ negabin[#] &]

A352319 Numbers whose minimal (or greedy) Pell representation (A317204) is palindromic.

Original entry on oeis.org

0, 1, 3, 6, 8, 13, 20, 30, 35, 40, 44, 49, 71, 88, 102, 119, 170, 182, 194, 204, 216, 238, 242, 254, 266, 276, 288, 409, 450, 484, 525, 559, 580, 621, 655, 696, 986, 1015, 1044, 1068, 1097, 1150, 1160, 1189, 1218, 1242, 1271, 1334, 1363, 1392, 1396, 1425, 1454
Offset: 1

Views

Author

Amiram Eldar, Mar 12 2022

Keywords

Comments

A052937(n) = A000129(n+1)+1 is a term for n>0, since its minimal Pell representation is 10...01 with n-1 0's between two 1's.
A048739 is a subsequence since these are repunit numbers in the minimal Pell representation.
A001109 is a subsequence. The minimal Pell representation of A001109(n), for n>1, is 1010...01, with n-1 0's interleaved with n 1's.

Examples

			The first 10 terms are:
   n  a(n)  A317204(a(n))
  --  ----  -------------
   1     0              0
   2     1              1
   3     3             11
   4     6            101
   5     8            111
   6    13           1001
   7    20           1111
   8    30          10001
   9    35          10101
  10    40          10201
		

Crossrefs

Subsequences: A001109, A048739, A052937 \ {2}.

Programs

  • Mathematica
    pell[1] = 1; pell[2] = 2; pell[n_] := pell[n] = 2*pell[n - 1] + pell[n - 2]; q[n_] := Module[{s = {}, m = n, k}, While[m > 0, k = 1; While[pell[k] <= m, k++]; k--; AppendTo[s, k]; m -= pell[k]; k = 1]; PalindromeQ[IntegerDigits[Total[3^(s - 1)], 3]]]; Select[Range[0, 1500], q]

A352341 Numbers whose maximal Pell representation (A352339) is palindromic.

Original entry on oeis.org

0, 1, 3, 6, 8, 10, 20, 27, 40, 49, 54, 58, 63, 68, 88, 93, 119, 136, 150, 167, 221, 238, 288, 300, 310, 322, 334, 338, 360, 372, 382, 394, 406, 508, 530, 542, 696, 737, 771, 812, 833, 867, 908, 942, 983, 1242, 1276, 1317, 1392, 1681, 1710, 1734, 1763, 1792, 1802
Offset: 1

Views

Author

Amiram Eldar, Mar 12 2022

Keywords

Comments

A000129(n) - 2 is a term for n > 1. The maximal Pell representations of these numbers are 0, 11, 121, 1221, 12221, ... (0 and A132583).
A048739 is a subsequence since these are the repunit numbers in the maximal Pell representation.
A065113 is a subsequence since the maximal Pell representation of A065113(n) is 2*n 2's.

Examples

			The first 10 terms are:
   n  a(n)  A352339(a(n))
  --  ----  -------------
   1    0               0
   2    1               1
   3    3              11
   4    6              22
   5    8             111
   6   10             121
   7   20            1111
   8   27            1221
   9   40            2222
  10   49           11111
		

Crossrefs

Programs

  • Mathematica
    pell[1] = 1; pell[2] = 2; pell[n_] := pell[n] = 2*pell[n - 1] + pell[n - 2]; pellp[n_] := Module[{s = {}, m = n, k}, While[m > 0, k = 1; While[pell[k] <= m, k++]; k--; AppendTo[s, k]; m -= pell[k]; k = 1]; IntegerDigits[Total[3^(s - 1)], 3]]; lazy[n_] := Module[{v = pellp[n]}, nv = Length[v]; i = 1; While[i <= nv - 2, If[v[[i]] > 0 && v[[i + 1]] == 0 && v[[i + 2]] < 2, v[[i ;; i + 2]] += {-1, 2, 1}; If[i > 2, i -= 3]]; i++]; i = Position[v, _?(# > 0 &)]; If[i == {}, 0, FromDigits[v[[i[[1, 1]] ;; -1]]]]]; Select[Range[0, 2000], PalindromeQ[lazy[#]] &]
Showing 1-10 of 30 results. Next