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 14 results. Next

A033014 Every run of digits of n in base 16 has length 2.

Original entry on oeis.org

17, 34, 51, 68, 85, 102, 119, 136, 153, 170, 187, 204, 221, 238, 255, 4352, 4386, 4403, 4420, 4437, 4454, 4471, 4488, 4505, 4522, 4539, 4556, 4573, 4590, 4607, 8704, 8721, 8755, 8772, 8789, 8806, 8823, 8840, 8857, 8874
Offset: 1

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Examples

			In base 16, a(1)=17 is written 11; the subsequent 14 values are the multiples of 17, corresponding to 22, 33, 44, ..., FF.
This is followed by a(16) = 4352 = 1100[16], then (still in base 16): 1122, 1133,..., 11FF, 2200, 2211, 2233, etc...
		

Crossrefs

See A033001 for further cross-references.

Programs

  • Mathematica
    Select[Range[9000],Union[Length/@Split[IntegerDigits[#,16]]]=={2}&] (* Harvey P. Dale, Jan 19 2013 *)
  • Python
    from itertools import count, islice, groupby
    def A033014_gen(startvalue=1): # generator of terms >= startvalue
        return filter(lambda n:set(len(list(g)) for k, g in groupby(hex(n)[2:]))=={2},count(max(startvalue,1)))
    A033014_list = list(islice(A033014_gen(),20)) # Chai Wah Wu, Mar 10 2023

Formula

a(n) = 17*A043320(n) (= 17n for n<16, cf Example). - M. F. Hasler, Feb 02 2014

A043307 a(n) = A033001(n)/4.

Original entry on oeis.org

1, 2, 9, 11, 18, 19, 82, 83, 99, 100, 163, 164, 171, 173, 738, 740, 747, 748, 892, 893, 900, 902, 1467, 1469, 1476, 1477, 1540, 1541, 1557, 1558, 6643, 6644, 6660, 6661, 6724, 6725, 6732, 6734, 8028, 8030, 8037, 8038, 8101, 8102, 8118, 8119
Offset: 1

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Comments

Also: Numbers which, written in base 9, have only digits 0, 1 or 2, and no two adjacent digits equal. - M. F. Hasler, Feb 03 2014

Crossrefs

Programs

  • Maple
    A[1]:= [1,2]:
    for d from 2 to 6 do
      A[d]:= map(t -> seq(9*t+j,j=subs(t mod 9 = NULL, [0,1,2])), A[d-1])
    od:
    seq(op(A[d]),d=1..6); # Robert Israel, Jan 29 2017
  • Mathematica
    Table[FromDigits[#,9]&/@Select[Tuples[{0,1,2},n],Min[Abs[Differences[#]]]>0&],{n,2,5}]// Flatten// Union (* Harvey P. Dale, May 27 2023 *)
  • PARI
    is_A043307(n)=(n=[n])&&!until(!n[1],((n=divrem(n[1],9))[2]<3 && n[1]%3!=n[2])||return) \\ M. F. Hasler, Feb 03 2014
    
  • PARI
    a(n) = my(v=binary(n+1)); v[1]=0; for(i=2,#v, v[i]+=(v[i]>=v[i-1])); fromdigits(v,9); \\ Kevin Ryde, Mar 13 2021

Formula

From Robert Israel, Jan 29 2017: (Start)
If a(n) == 0 (mod 3) then a(2*n+1) = 9*a(n) + 1 else a(2*n+1) = 9*a(n).
If a(n) == 2 (mod 3) then a(2*n+2) = 9*a(n) + 1 else a(2*n+1) = 9*a(n)+2.
a(4k+5) = 9*a(2k+2).
(End)

A043308 a(n)=A033002(n)/5.

Original entry on oeis.org

1, 2, 3, 16, 18, 19, 32, 33, 35, 48, 49, 50, 257, 258, 259, 288, 289, 291, 304, 305, 306, 513, 514, 515, 528, 530, 531, 560, 561, 562, 769, 770, 771, 784, 786, 787, 800, 801, 803, 4112, 4114, 4115, 4128, 4129, 4131, 4144, 4145
Offset: 1

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Comments

Also: Numbers which, written in base 16, have all digits less than 4 and no two adjacent digits equal. - M. F. Hasler, Feb 03 2014

Crossrefs

Programs

  • PARI
    is_A043308(n)=(n=[n])&&!until(!n[1],((n=divrem(n[1],16))[2]<4 && n[1]%4!=n[2])||return) \\ M. F. Hasler, Feb 03 2014

A043312 a(n) = A033006(n)/9.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 64, 66, 67, 68, 69, 70, 71, 128, 129, 131, 132, 133, 134, 135, 192, 193, 194, 196, 197, 198, 199, 256, 257, 258, 259, 261, 262, 263, 320, 321, 322, 323, 324, 326, 327, 384, 385, 386, 387, 388, 389, 391, 448, 449
Offset: 1

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Comments

Also: Numbers which, written in base 64, have only digits 0 through 7, and no two adjacent digits equal. - M. F. Hasler, Feb 03 2014

Crossrefs

Programs

  • Maple
    f:= proc(n) local i;
          seq(64*n+i, i= subs(n mod 64 = NULL, [$0..7]))
    end proc:
    A:= $1..7: R:= [A]:
    for d from 2 to 3 do
      R:= map(f, R);
      A:= A, op(R);
    od:
    A; # Robert Israel, Jun 11 2019
  • PARI
    is_A043312(n)=(n=[n])&&!until(!n[1],((n=divrem(n[1],64))[2]<8 && n[1]%8!=n[2])||return) \\ M. F. Hasler, Feb 03 2014

A043317 a(n)=A033011(n)/14.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 169, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 338, 339, 341, 342, 343, 344, 345, 346, 347, 348, 349, 350, 507, 508, 509, 511, 512, 513, 514, 515, 516, 517, 518, 519, 676, 677, 678
Offset: 1

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Comments

Also: Numbers which, written in base 169, have all digits less than 13 and no two adjacent digits equal. - M. F. Hasler, Feb 03 2014

Crossrefs

Programs

  • Mathematica
    Select[Range[700],Max[IntegerDigits[#,169]]<13&&SequenceCount[ IntegerDigits[ #,169],{x_,x_}]==0&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 07 2018 *)
  • PARI
    is_A043317(n)=(n=[n])&&!until(!n[1],((n=divrem(n,169))[2]<13 && n[2]!=n[1]%13)||return) \\ M. F. Hasler, Feb 03 2014

A043319 a(n)=A033013(n)/16.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 225, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 450, 451, 453, 454, 455, 456, 457, 458, 459, 460, 461, 462, 463, 464, 675, 676, 677, 679, 680, 681, 682, 683, 684
Offset: 1

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Comments

Also: Numbers which, written in base 225, have all digits less than 15 and no two adjacent digits equal. - M. F. Hasler, Feb 03 2014

Crossrefs

Programs

  • PARI
    is_A043319(n)=(n=[n])&&!until(!n[1], ((n=divrem(n[1], 225))[2]<15 && n[1]%15!=n[2])||return) \\ M. F. Hasler, Feb 03 2014

A043309 a(n)=A033003(n)/6.

Original entry on oeis.org

1, 2, 3, 4, 25, 27, 28, 29, 50, 51, 53, 54, 75, 76, 77, 79, 100, 101, 102, 103, 626, 627, 628, 629, 675, 676, 678, 679, 700, 701, 702, 704, 725, 726, 727, 728, 1251, 1252, 1253, 1254, 1275, 1277, 1278, 1279, 1325, 1326, 1327, 1329
Offset: 1

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Comments

Also: Numbers which, written in base 25, have all digits less than 5 and no two adjacent digits equal. - M. F. Hasler, Feb 03 2014

Crossrefs

Programs

  • PARI
    is_A043309(n)=(n=[n])&&!until(!n[1],((n=divrem(n[1],25))[2]<5 && n[1]%5!=n[2])||return) \\ M. F. Hasler, Feb 03 2014

A043310 a(n)=A033004(n)/7.

Original entry on oeis.org

1, 2, 3, 4, 5, 36, 38, 39, 40, 41, 72, 73, 75, 76, 77, 108, 109, 110, 112, 113, 144, 145, 146, 147, 149, 180, 181, 182, 183, 184, 1297, 1298, 1299, 1300, 1301, 1368, 1369, 1371, 1372, 1373, 1404, 1405, 1406, 1408, 1409, 1440, 1441, 1442, 1443, 1445, 1476, 1477
Offset: 1

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Comments

Also: Numbers which, written in base 36, have all digits less than 6 and no two adjacent digits equal. - M. F. Hasler, Feb 03 2014

Crossrefs

Programs

  • PARI
    is_A043310(n)=(n=[n])&&!until(!n[1],((n=divrem(n[1],36))[2]<6 && n[1]%6!=n[2])||return) \\ M. F. Hasler, Feb 03 2014

Extensions

Definition corrected by and more terms from Georg Fischer, Mar 04 2021

A043311 a(n)=A033005(n)/8.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 49, 51, 52, 53, 54, 55, 98, 99, 101, 102, 103, 104, 147, 148, 149, 151, 152, 153, 196, 197, 198, 199, 201, 202, 245, 246, 247, 248, 249, 251, 294, 295, 296, 297, 298, 299, 2402, 2403, 2404, 2405, 2406, 2407, 2499
Offset: 1

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Comments

Numbers which, written in base 49, have only digits 0 through 6 and no two adjacent digits equal. - M. F. Hasler, Feb 03 2014

Crossrefs

Programs

  • PARI
    is_A043311(n)=(n=[n])&&!until(!n[1],((n=divrem(n[1],49))[2]<7 && n[1]%7!=n[2])||return) \\ M. F. Hasler, Feb 03 2014

A043313 a(n)=A033007(n)/10.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 81, 83, 84, 85, 86, 87, 88, 89, 162, 163, 165, 166, 167, 168, 169, 170, 243, 244, 245, 247, 248, 249, 250, 251, 324, 325, 326, 327, 329, 330, 331, 332, 405, 406, 407, 408, 409, 411, 412, 413, 486, 487, 488
Offset: 1

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Author

Keywords

Comments

Also: Numbers which, written in base 81, have only digits 0,...,8, and no two adjacent digits equal. - M. F. Hasler, Feb 03 2014

Crossrefs

Programs

  • PARI
    is_A043313(n)=(n=[n])&&!until(!n[1],((n=divrem(n[1],81))[2]<9 && n[1]%9!=n[2])||return) \\ M. F. Hasler, Feb 03 2014
Showing 1-10 of 14 results. Next