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 1-4 of 4 results.

A277543 a(n) = n/5^m mod 5, where 5^m is the greatest power of 5 that divides n.

Original entry on oeis.org

1, 2, 3, 4, 1, 1, 2, 3, 4, 2, 1, 2, 3, 4, 3, 1, 2, 3, 4, 4, 1, 2, 3, 4, 1, 1, 2, 3, 4, 1, 1, 2, 3, 4, 2, 1, 2, 3, 4, 3, 1, 2, 3, 4, 4, 1, 2, 3, 4, 2, 1, 2, 3, 4, 1, 1, 2, 3, 4, 2, 1, 2, 3, 4, 3, 1, 2, 3, 4, 4, 1, 2, 3, 4, 3, 1, 2, 3, 4, 1, 1, 2, 3, 4, 2, 1
Offset: 1

Views

Author

Clark Kimberling, Oct 19 2016

Keywords

Comments

a(n) is the rightmost nonzero digit in the base 5 expansion of n (A007091).

Examples

			a(20) = (20/5 mod 5) = 4.

Links

Crossrefs

Cf. A007091, A010874, A132739.
Cf. A277550, A277551, A277555, A277548 (positions of 1, 2, 3 and 4 in this sequence).

Programs

  • Mathematica
    Table[Mod[n/5^IntegerExponent[n, 5], 5], {n, 1, 160}]
  • PARI
    a(n) = n/5^valuation(n, 5) % 5; \\ Michel Marcus, Oct 20 2016

Formula

a(n) = A132739(n) mod 5 = A010874(A132739(n)). - Michel Marcus, Oct 20 2016

A277550 Numbers k such that k/5^m == 1 (mod 5), where 5^m is the greatest power of 5 that divides k.

Original entry on oeis.org

1, 5, 6, 11, 16, 21, 25, 26, 30, 31, 36, 41, 46, 51, 55, 56, 61, 66, 71, 76, 80, 81, 86, 91, 96, 101, 105, 106, 111, 116, 121, 125, 126, 130, 131, 136, 141, 146, 150, 151, 155, 156, 161, 166, 171, 176, 180, 181, 186, 191, 196, 201, 205, 206, 211, 216, 221
Offset: 1

Views

Author

Clark Kimberling, Oct 20 2016

Keywords

Comments

Positions of 1 in A277543. Numbers that have 1 as their rightmost nonzero digit when written in base 5.
This is one sequence in a 4-way splitting of the positive integers; the other three are indicated in the Mathematica program.

Links

Crossrefs

Cf. A277543, A277551, A277555, A277548.

Programs

  • Mathematica
    z = 200; a[b_] := Table[Mod[n/b^IntegerExponent[n, b], b], {n, 1, z}]
p[b_, d_] := Flatten[Position[a[b], d]]
p[5, 1] (* A277550 *)
p[5, 2] (* A277551 *)
p[5, 3] (* A277555 *)
p[5, 4] (* A277548 *)
  • PARI
    isok(n) = n/5^valuation(n, 5) % 5 == 1; \\ Michel Marcus, Oct 21 2016

A277551 Numbers k such that k/5^m == 2 (mod 5), where 5^m is the greatest power of 5 that divides k.

Original entry on oeis.org

2, 7, 10, 12, 17, 22, 27, 32, 35, 37, 42, 47, 50, 52, 57, 60, 62, 67, 72, 77, 82, 85, 87, 92, 97, 102, 107, 110, 112, 117, 122, 127, 132, 135, 137, 142, 147, 152, 157, 160, 162, 167, 172, 175, 177, 182, 185, 187, 192, 197, 202, 207, 210, 212, 217, 222, 227
Offset: 1

Views

Author

Clark Kimberling, Oct 20 2016

Keywords

Comments

Positions of 2 in A277543. Numbers that have 2 as their rightmost nonzero digit when written in base 5.
This is one sequence in a 4-way splitting of the positive integers; the other three are indicated in the Mathematica program.

Links

Crossrefs

Cf. A277543, A277550, A277555, A277548.

Programs

  • Mathematica
    z = 200; a[b_] := Table[Mod[n/b^IntegerExponent[n, b], b], {n, 1, z}]
p[b_, d_] := Flatten[Position[a[b], d]]
p[5, 1] (* A277550 *)
p[5, 2] (* A277551 *)
p[5, 3] (* A277555 *)
p[5, 4] (* A277548 *)
  • PARI
    isok(n) = n/5^valuation(n, 5) % 5 == 2; \\ Michel Marcus, Oct 21 2016

A277555 Numbers k such that k/5^m == 3 (mod 5), where 5^m is the greatest power of 5 that divides k.

Original entry on oeis.org

3, 8, 13, 15, 18, 23, 28, 33, 38, 40, 43, 48, 53, 58, 63, 65, 68, 73, 75, 78, 83, 88, 90, 93, 98, 103, 108, 113, 115, 118, 123, 128, 133, 138, 140, 143, 148, 153, 158, 163, 165, 168, 173, 178, 183, 188, 190, 193, 198, 200, 203, 208, 213, 215, 218, 223, 228
Offset: 1

Views

Author

Clark Kimberling, Oct 20 2016

Keywords

Comments

Positions of 3 in A277543. Numbers that have 3 as their rightmost nonzero digit when written in base 5.
This is one sequence in a 4-way splitting of the positive integers; the other three are indicated in the Mathematica program.

Links

Crossrefs

Cf. A132739, A277543, A277550, A277551, A277548.

Programs

  • Mathematica
    z = 200; a[b_] := Table[Mod[n/b^IntegerExponent[n, b], b], {n, 1, z}]
p[b_, d_] := Flatten[Position[a[b], d]]
p[5, 1] (* A277550 *)
p[5, 2] (* A277551 *)
p[5, 3] (* A277555 *)
p[5, 4] (* A277548 *)
  • PARI
    isok(n) = n/5^valuation(n, 5) % 5 == 3; \\ Michel Marcus, Oct 20 2016
Showing 1-4 of 4 results.

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