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.

A129318 a(n) = sopfr(A129316(n)), where sopfr(x) is the sum of the prime factors of x, counting multiplicity.

Original entry on oeis.org

5, 6, 8, 18, 15, 15, 17, 39, 29, 86, 23, 35, 25, 22, 33, 68, 26, 31, 46, 32, 37, 24, 35, 23, 45, 100, 78, 51, 39, 45, 44, 33, 35, 45, 98, 34, 45, 141, 147, 67, 25, 43, 236, 25, 29, 75, 150, 29, 76, 125, 160, 26, 121, 122, 73, 37, 52, 56, 40, 39, 54, 58, 239, 69, 36, 39
Offset: 1

Views

Author

Walter Kehowski, Apr 09 2007, corrected Apr 09 2007

Keywords

Examples

			a(6)=15 since sopfr(A129316(6))=sopfr(160)=sopfr(2^5*5)=15.

Links

Crossrefs

Cf. A001414, A006145, A039752, A129316, A129317, A129319, A129320.

A129317 The second of the pair of consecutive integers k and k+1 such that sopfr(k) divides sopfr(k+1), where sopfr(k) is the sum of the prime factors of k, counting multiplicity.

Original entry on oeis.org

6, 9, 16, 78, 126, 161, 253, 497, 715, 949, 981, 1046, 1054, 1261, 1331, 1379, 1405, 1431, 1509, 1521, 1611, 1751, 1863, 1891, 2171, 2492, 2681, 2822, 3095, 3101, 3249, 3401, 3592, 3611, 3653, 3809, 4186, 4192, 4385, 4453, 4501, 4599, 4907, 5121, 5146
Offset: 1

Views

Author

Walter Kehowski, Apr 09 2007

Keywords

Comments

A129316 is the first element of the pair.
A generalization of Ruth-Aaron pairs (A006145).

Examples

			a(6)=161 since sopfr(160)=sopfr(2^5*5)=10+5=15 and sopfr(161)=sopfr(7*23)=30.

Links

Crossrefs

Cf. A001414, A006145, A039752, A129316, A129318, A129319.

Formula

sopfr(k+1) mod sopfr(k) = 0.
a(n) = A129316(n+1). - Amiram Eldar, Oct 26 2019

A129319 a(n) = sopfr(A129317(n)), where sopfr(x) is the sum of the prime factors of x, counting multiplicity.

Original entry on oeis.org

5, 6, 8, 18, 15, 30, 34, 78, 29, 86, 115, 525, 50, 110, 33, 204, 286, 62, 506, 32, 185, 120, 35, 92, 180, 100, 390, 102, 624, 450, 44, 198, 455, 180, 294, 306, 45, 141, 882, 134, 650, 86, 708, 575, 116, 75, 150, 174, 152, 375, 160, 286, 242, 122, 584, 518, 1456, 448
Offset: 1

Views

Author

Walter Kehowski, Apr 09 2007

Keywords

Examples

			a(6)=30 since sopfr(A129317(6))=sopfr(161)=sopfr(7*23)=30.

Links

Crossrefs

Cf. A001414, A006145, A039752, A129316, A129317, A129318, A129320.

A129320 a(n) = A129319(n)/A129318(n).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 5, 15, 2, 5, 1, 3, 11, 2, 11, 1, 5, 5, 1, 4, 4, 1, 5, 2, 16, 10, 1, 6, 13, 4, 3, 9, 1, 1, 6, 2, 26, 2, 3, 23, 4, 1, 1, 6, 2, 3, 1, 11, 2, 1, 8, 14, 28, 8, 1, 7, 1, 23, 8, 20, 7, 2
Offset: 1

Views

Author

Walter Kehowski, Apr 09 2007

Keywords

Examples

			a(6)=2 since A129319(n)/A129318(n)=30/15=2.

Links

Crossrefs

Cf. A001414, A006145, A039752, A129316, A129317, A129318, A129319.
Showing 1-4 of 4 results.

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

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