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 15 results. Next

A277593 Numbers k such that k/10^m == 6 mod 10, where 10^m is the greatest power of 10 that divides n.

Original entry on oeis.org

6, 16, 26, 36, 46, 56, 60, 66, 76, 86, 96, 106, 116, 126, 136, 146, 156, 160, 166, 176, 186, 196, 206, 216, 226, 236, 246, 256, 260, 266, 276, 286, 296, 306, 316, 326, 336, 346, 356, 360, 366, 376, 386, 396, 406, 416, 426, 436, 446, 456, 460, 466, 476, 486
Offset: 1

Views

Author

Clark Kimberling, Nov 07 2016

Keywords

Comments

Positions of 6 in A065881.
Numbers having 6 as rightmost nonzero digit in base 10. This is one sequence in a 10-way splitting of the positive integers; the other nine are indicated in the Mathematica program.

Crossrefs

Programs

A277589 Numbers k such that k/10^m == 2 mod 10, where 10^m is the greatest power of 10 that divides n.

Original entry on oeis.org

2, 12, 20, 22, 32, 42, 52, 62, 72, 82, 92, 102, 112, 120, 122, 132, 142, 152, 162, 172, 182, 192, 200, 202, 212, 220, 222, 232, 242, 252, 262, 272, 282, 292, 302, 312, 320, 322, 332, 342, 352, 362, 372, 382, 392, 402, 412, 420, 422, 432, 442, 452, 462, 472
Offset: 1

Views

Author

Clark Kimberling, Nov 05 2016

Keywords

Comments

Positions of 2 in A065881.
Numbers having 2 as rightmost nonzero digit in base 10. This is one sequence in a 10-way splitting of the positive integers; the other nine are indicated in the Mathematica program.

Crossrefs

Programs

A277591 Numbers k such that k/10^m == 4 mod 10, where 10^m is the greatest power of 10 that divides n.

Original entry on oeis.org

4, 14, 24, 34, 40, 44, 54, 64, 74, 84, 94, 104, 114, 124, 134, 140, 144, 154, 164, 174, 184, 194, 204, 214, 224, 234, 240, 244, 254, 264, 274, 284, 294, 304, 314, 324, 334, 340, 344, 354, 364, 374, 384, 394, 400, 404, 414, 424, 434, 440, 444, 454, 464, 474
Offset: 1

Views

Author

Clark Kimberling, Nov 05 2016

Keywords

Comments

Positions of 4 in A065881.
Numbers having 4 as rightmost nonzero digit in base 10. This is one sequence in a 10-way splitting of the positive integers; the other nine are indicated in the Mathematica program.

Crossrefs

Programs

  • Mathematica
    z = 460; a[b_] := Table[Mod[n/b^IntegerExponent[n, b], b], {n, 1, z}]
    p[b_, d_] := Flatten[Position[a[b], d]]
    p[10, 1] (* A277588 *)
    p[10, 2] (* A277589 *)
    p[10, 3] (* A277590 *)
    p[10, 4] (* A277591 *)
    p[10, 5] (* A277592 *)
    p[10, 6] (* A277593 *)
    p[10, 7] (* A277594 *)
    p[10, 8] (* A277595 *)
    p[10, 9] (* A277596 *)

A277592 Numbers k such that k/10^m == 5 mod 10, where 10^m is the greatest power of 10 that divides n.

Original entry on oeis.org

5, 15, 25, 35, 45, 50, 55, 65, 75, 85, 95, 105, 115, 125, 135, 145, 150, 155, 165, 175, 185, 195, 205, 215, 225, 235, 245, 250, 255, 265, 275, 285, 295, 305, 315, 325, 335, 345, 350, 355, 365, 375, 385, 395, 405, 415, 425, 435, 445, 450, 455, 465, 475, 485
Offset: 1

Views

Author

Clark Kimberling, Nov 05 2016

Keywords

Comments

Positions of 5 in A065881.
Numbers having 5 as rightmost nonzero digit in base 10. This is one sequence in a 10-way splitting of the positive integers; the other nine are indicated in the Mathematica program.
This sequence differs from A121025, which includes 540.

Crossrefs

Programs

  • Mathematica
    z = 460; a[b_] := Table[Mod[n/b^IntegerExponent[n, b], b], {n, 1, z}]
    p[b_, d_] := Flatten[Position[a[b], d]]
    p[10, 1] (* A277588 *)
    p[10, 2] (* A277589 *)
    p[10, 3] (* A277590 *)
    p[10, 4] (* A277591 *)
    p[10, 5] (* A277592 *)
    p[10, 6] (* A277593 *)
    p[10, 7] (* A277594 *)
    p[10, 8] (* A277595 *)
    p[10, 9] (* A277596 *)

A277595 Numbers k such that k/10^m == 8 mod 10, where 10^m is the greatest power of 10 that divides k.

Original entry on oeis.org

8, 18, 28, 38, 48, 58, 68, 78, 80, 88, 98, 108, 118, 128, 138, 148, 158, 168, 178, 180, 188, 198, 208, 218, 228, 238, 248, 258, 268, 278, 280, 288, 298, 308, 318, 328, 338, 348, 358, 368, 378, 380, 388, 398, 408, 418, 428, 438, 448, 458, 468, 478, 480, 488
Offset: 1

Views

Author

Clark Kimberling, Nov 07 2016

Keywords

Comments

Positions of 8 in A065881.
Numbers having 8 as rightmost nonzero digit in base 10. This is one sequence in a 10-way splitting of the positive integers; the other nine are indicated in the Mathematica program.

Crossrefs

Programs

  • Mathematica
    z = 460; a[b_] := Table[Mod[n/b^IntegerExponent[n, b], b], {n, 1, z}]
    p[b_, d_] := Flatten[Position[a[b], d]]
    p[10, 1] (* A277588 *)
    p[10, 2] (* A277589 *)
    p[10, 3] (* A277590 *)
    p[10, 4] (* A277591 *)
    p[10, 5] (* A277592 *)
    p[10, 6] (* A277593 *)
    p[10, 7] (* A277594 *)
    p[10, 8] (* A277595 *)
    p[10, 9] (* A277596 *)
    fQ[n_]:=Module[{sp=Split[IntegerDigits[n]]},If[MemberQ[sp[[-1]],0],sp = Drop[ sp, -1]];MemberQ[sp[[-1]],8]]; Select[Range[500],fQ] (* Harvey P. Dale, Sep 14 2018 *)
  • PARI
    is(n)=n && n/10^valuation(n,10)%10==6 \\ Charles R Greathouse IV, Jan 31 2017

A065882 Ultimate modulo 4: right-hand nonzero digit of n when written in base 4.

Original entry on oeis.org

1, 2, 3, 1, 1, 2, 3, 2, 1, 2, 3, 3, 1, 2, 3, 1, 1, 2, 3, 1, 1, 2, 3, 2, 1, 2, 3, 3, 1, 2, 3, 2, 1, 2, 3, 1, 1, 2, 3, 2, 1, 2, 3, 3, 1, 2, 3, 3, 1, 2, 3, 1, 1, 2, 3, 2, 1, 2, 3, 3, 1, 2, 3, 1, 1, 2, 3, 1, 1, 2, 3, 2, 1, 2, 3, 3, 1, 2, 3, 1, 1, 2, 3, 1, 1, 2, 3, 2, 1, 2, 3, 3, 1, 2, 3, 2, 1, 2, 3, 1, 1, 2, 3, 2, 1
Offset: 1

Views

Author

Henry Bottomley, Nov 26 2001

Keywords

Comments

From Bradley Klee, Sep 12 2015: (Start)
In some guise, this sequence is a linear encoding of the three fixed-point half-hex tilings (cf. Baake & Grimm, Frettlöh). Applying a permutation, morphism x -> 123x becomes x -> x123, which has three fixed points. Applying a partition, morphism x -> x123 becomes x ->{{3,2},{x,1}} or
3 2 3 2
3 1 2 1
3 2 3 2 3 2
x -> x 1 -> x 1 1 1 -> etc.,
which is the substitution rule for the half-hex tiling when the numbers 1,2,3 determine the direction of a dissecting diameter inscribed on each hexagon.
(End)

Examples

			a(7)=3 and a(112)=3, since 7 is written in base 4 as 13 and 112 as 1300.
		

References

  • M. Baake and U. Grimm, Aperiodic Order Vol. 1, Cambridge University Press, 2013, page 205.

Crossrefs

In base 2 this is A000012, base 3 A060236 and base 10 A065881.
Defining relations for g.f. similar to A014577.

Programs

  • Maple
    f:= proc(n)
    local x:=n;
       while x mod 4 = 0 do x:= x/4 od:
       x mod 4;
    end proc;
    map(f, [$1..100]); # Robert Israel, Jan 05 2016
  • Mathematica
    Nest[ Flatten[ # /. {1 -> {1, 2, 3, 1}, 2 -> {1, 2, 3, 2}, 3 -> {1, 2, 3, 3}}] &, {1}, 4] (* Robert G. Wilson v, May 07 2005 *)
    b[n_] := CoefficientList[Series[
        With[{f0 = (x + 2 x^2 + 3 x^3)/(1 - x^4)},
         Nest[ (# /. x -> x^4) + f0 &, f0, Ceiling[Log[4, n/3]]]],
    {x, 0, n}], x][[2 ;; -1]]; b[100](* Bradley Klee, Sep 12 2015 *)
    Table[Mod[n/4^IntegerExponent[n, 4], 4], {n, 1, 120}] (* Clark Kimberling, Oct 19 2016 *)
  • PARI
    a(n) = (n/4^valuation(n,4))%4; \\ Joerg Arndt, Sep 13 2015
    
  • Python
    def A065882(n): return (n>>((~n & n-1).bit_length()&-2))&3 # Chai Wah Wu, Aug 21 2023

Formula

If n mod 4 = 0 then a(n) = a(n/4), otherwise a(n) = n mod 4. a(n) = A065883(n) mod 4.
Fixed point of the morphism: 1 ->1231, 2 ->1232, 3 ->1233, starting from a(1) = 1. Sequence read mod 2 gives A035263. a(n) = A007913(n) mod 4. - Philippe Deléham, Mar 28 2004
G.f. g(x) satisfies g(x) = g(x^4) + (x + 2 x^2 + 3 x^3)/(1 - x^4). - Bradley Klee, Sep 12 2015

A162501 Lexicographically earliest permutation of the natural numbers such that in decimal representation the initial digit for each term is equal to the last nonzero digit of its predecessor; a(1)=1.

Original entry on oeis.org

1, 10, 11, 12, 2, 20, 21, 13, 3, 30, 31, 14, 4, 40, 41, 15, 5, 50, 51, 16, 6, 60, 61, 17, 7, 70, 71, 18, 8, 80, 81, 19, 9, 90, 91, 100, 101, 102, 22, 23, 32, 24, 42, 25, 52, 26, 62, 27, 72, 28, 82, 29, 92, 200, 201, 103, 33, 34, 43, 35, 53, 36, 63, 37, 73, 38, 83, 39, 93, 300, 301
Offset: 1

Views

Author

Reinhard Zumkeller, Jul 05 2009

Keywords

Comments

A000030(a(n+1)) = A065881(a(n));
inverse of A162502: a(A162502(n)) = A162502(a(n)) = n;
a(a(n)) = A162503(n).

Crossrefs

A277588 Numbers k such that k/10^m == 1 mod 10, where 10^m is the greatest power of 10 that divides n.

Original entry on oeis.org

1, 10, 11, 21, 31, 41, 51, 61, 71, 81, 91, 100, 101, 110, 111, 121, 131, 141, 151, 161, 171, 181, 191, 201, 210, 211, 221, 231, 241, 251, 261, 271, 281, 291, 301, 310, 311, 321, 331, 341, 351, 361, 371, 381, 391, 401, 410, 411, 421, 431, 441, 451, 461, 471
Offset: 1

Views

Author

Clark Kimberling, Nov 05 2016

Keywords

Comments

Positions of 1 in A065881.
Numbers having 1 as rightmost nonzero digit in base 10. This is one sequence in a 10-way splitting of the positive integers; the other nine are indicated in the Mathematica program.

Crossrefs

Programs

  • Maple
    M:= 4: # to get all terms with <= M digits
    A:= sort([seq(seq(10^d*(10*x+1),x=0..10^(M-1-d)-1),d=0..M-2)]); # Robert Israel, Nov 07 2016
  • Mathematica
    z = 460; a[b_] := Table[Mod[n/b^IntegerExponent[n, b], b], {n, 1, z}]
    p[b_, d_] := Flatten[Position[a[b], d]]
    p[10, 1] (* A277588 *)
    p[10, 2] (* A277589 *)
    p[10, 3] (* A277590 *)
    p[10, 4] (* A277591 *)
    p[10, 5] (* A277592 *)
    p[10, 6] (* A277593 *)
    p[10, 7] (* A277594 *)
    p[10, 8] (* A277595 *)
    p[10, 9] (* A277596 *)
    f[n_] := Block[{m = n}, While[ Mod[m, 10] == 0, m /= 10]; Mod[m, 10]]; Flatten@ Position[ Array[f, 500], 1] (* Robert G. Wilson v, Nov 06 2016 *)
  • PARI
    is(n)=n && n/10^valuation(n,10)%10==1 \\ Charles R Greathouse IV, Jan 31 2017

A277590 Numbers k such that k/10^m == 3 mod 10, where 10^m is the greatest power of 10 that divides n.

Original entry on oeis.org

3, 13, 23, 30, 33, 43, 53, 63, 73, 83, 93, 103, 113, 123, 130, 133, 143, 153, 163, 173, 183, 193, 203, 213, 223, 230, 233, 243, 253, 263, 273, 283, 293, 300, 303, 313, 323, 330, 333, 343, 353, 363, 373, 383, 393, 403, 413, 423, 430, 433, 443, 453, 463, 473
Offset: 1

Views

Author

Clark Kimberling, Nov 05 2016

Keywords

Comments

Positions of 3 in A065881.
Numbers having 3 as rightmost nonzero digit in base 10. This is one sequence in a 10-way splitting of the positive integers; the other nine are indicated in the Mathematica program.

Crossrefs

Programs

A277594 Numbers k such that k/10^m == 7 mod 10, where 10^m is the greatest power of 10 that divides n.

Original entry on oeis.org

7, 17, 27, 37, 47, 57, 67, 70, 77, 87, 97, 107, 117, 127, 137, 147, 157, 167, 170, 177, 187, 197, 207, 217, 227, 237, 247, 257, 267, 270, 277, 287, 297, 307, 317, 327, 337, 347, 357, 367, 370, 377, 387, 397, 407, 417, 427, 437, 447, 457, 467, 470, 477, 487
Offset: 1

Views

Author

Clark Kimberling, Nov 07 2016

Keywords

Comments

Positions of 7 in A065881.
Numbers having 7 as rightmost nonzero digit in base 10. This is one sequence in a 10-way splitting of the positive integers; the other nine are indicated in the Mathematica program.

Crossrefs

Programs

Showing 1-10 of 15 results. Next