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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.

A326391 Lesser of twin primes p >= 3 for which sigma(p+1)/sigma(p-1) reaches record value, where sigma(n) is the divisor sum function (A000203).

Table of values

n a(n)
1 3
2 7559
3 42839
4 55439
5 110879
6 415799
7 1713599
8 1940399
9 2489759
10 6652799
11 6846839
12 15855839
13 31600799
14 85765679
15 232792559
16 845404559
17 1470268799
18 6299092799
19 10708457759
20 17459441999
21 32125373279
22 135019684799
23 439977938399
24 449755225919
25 1799020903679
26 2126560035599
27 2835413380799
28 6278415343199

List of values

[3, 7559, 42839, 55439, 110879, 415799, 1713599, 1940399, 2489759, 6652799, 6846839, 15855839, 31600799, 85765679, 232792559, 845404559, 1470268799, 6299092799, 10708457759, 17459441999, 32125373279, 135019684799, 439977938399, 449755225919, 1799020903679, 2126560035599, 2835413380799, 6278415343199]

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

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