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.

A083714 (greatest prime <= n) - (greatest prime factor of n).

Original entry on oeis.org

0, 0, 0, 1, 0, 2, 0, 5, 4, 2, 0, 8, 0, 6, 8, 11, 0, 14, 0, 14, 12, 8, 0, 20, 18, 10, 20, 16, 0, 24, 0, 29, 20, 14, 24, 28, 0, 18, 24, 32, 0, 34, 0, 32, 38, 20, 0, 44, 40, 42, 30, 34, 0, 50, 42, 46, 34, 24, 0, 54, 0, 30, 54, 59, 48, 50, 0, 50, 44, 60, 0, 68, 0, 36, 68, 54, 62, 60, 0, 74
Offset: 1

Views

Author

Reinhard Zumkeller, May 04 2003

Keywords

Comments

a(n) = A007917(n) - A006530(n);
n>1: a(n) = 0 iff n is prime.

Crossrefs

Cf. A083718, A083715, A083716, A083717.

Programs

  • Mathematica
    Join[{0},Table[NextPrime[n+1,-1]-FactorInteger[n][[-1,1]],{n,2,90}]] (* Harvey P. Dale, Nov 27 2011 *)

A083715 (greatest prime <= n) mod (greatest prime factor of n).

Original entry on oeis.org

0, 0, 0, 1, 0, 2, 0, 1, 1, 2, 0, 2, 0, 6, 3, 1, 0, 2, 0, 4, 5, 8, 0, 2, 3, 10, 2, 2, 0, 4, 0, 1, 9, 14, 3, 1, 0, 18, 11, 2, 0, 6, 0, 10, 3, 20, 0, 2, 5, 2, 13, 8, 0, 2, 9, 4, 15, 24, 0, 4, 0, 30, 5, 1, 9, 6, 0, 16, 21, 4, 0, 2, 0, 36, 3, 16, 7, 8, 0, 4, 1, 38, 0, 6, 15, 40, 25, 6, 0, 4, 11, 20, 27, 42
Offset: 1

Views

Author

Reinhard Zumkeller, May 04 2003

Keywords

Comments

a(n) = A007917(n) mod A006530(n);
n>1: a(n) = 0 iff n is prime.

Crossrefs

Cf. A083716, A083717, A083714, A083718.

A083717 (Greatest prime <= n) * (greatest prime factor of n).

Original entry on oeis.org

1, 4, 9, 6, 25, 15, 49, 14, 21, 35, 121, 33, 169, 91, 65, 26, 289, 51, 361, 95, 133, 209, 529, 69, 115, 299, 69, 161, 841, 145, 961, 62, 341, 527, 217, 93, 1369, 703, 481, 185, 1681, 287, 1849, 473, 215, 989, 2209, 141, 329, 235, 799, 611, 2809, 159, 583, 371
Offset: 1

Views

Author

Reinhard Zumkeller, May 04 2003

Keywords

Comments

a(n) = A007917(n)*A006530(n);
Terms of A001358; A001248 is a subsequence.

Crossrefs

Cf. A083715, A083716, A083714 A083718.

A083718 (greatest prime <= n) + (greatest prime factor of n).

Original entry on oeis.org

2, 4, 6, 5, 10, 8, 14, 9, 10, 12, 22, 14, 26, 20, 18, 15, 34, 20, 38, 24, 26, 30, 46, 26, 28, 36, 26, 30, 58, 34, 62, 33, 42, 48, 38, 34, 74, 56, 50, 42, 82, 48, 86, 54, 48, 66, 94, 50, 54, 52, 64, 60, 106, 56, 64, 60, 72, 82, 118, 64, 122, 92, 68, 63, 74, 72, 134, 84, 90, 74
Offset: 1

Views

Author

Reinhard Zumkeller, May 04 2003

Keywords

Comments

a(n) = A007917(n) + A006530(n).

Crossrefs

Cf. A083714, A083715, A083716, A083717.

Programs

  • Mathematica
    Join[{2},Table[If[PrimeQ[n],n,NextPrime[n,-1]]+FactorInteger[n][[-1,1]],{n,2,70}]] (* Harvey P. Dale, Aug 11 2016 *)
Showing 1-4 of 4 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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