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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.

A154704 a(n) = smallest number k such that k-1 and k+1 both have exactly n prime divisors (counted with multiplicity).

Table of values

n a(n)
1 4
2 5
3 19
4 55
5 271
6 1889
7 10529
8 59777
9 101249
10 406783
11 6581249
12 12164095
13 65071999
14 652963841
15 6548416001
16 13858918399
17 145046192129
18 75389157377
19 943344975871
20 23114453401601
21 108772434771967
22 101249475018751
23 551785225781249
24 9740041658826751
25 136182187711004671
26 4560483868737535

List of values

[4, 5, 19, 55, 271, 1889, 10529, 59777, 101249, 406783, 6581249, 12164095, 65071999, 652963841, 6548416001, 13858918399, 145046192129, 75389157377, 943344975871, 23114453401601, 108772434771967, 101249475018751, 551785225781249, 9740041658826751, 136182187711004671, 4560483868737535]

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

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