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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.

A348420 a(n) = Product_{k=1..n} (p_k - 1)/2 where p_1, p_2, ..., p_n are the first n primes congruent to 3 modulo 4.

Table of values

n a(n)
0 1
1 1
2 3
3 15
4 135
5 1485
6 22275
7 467775
8 10758825
9 312005925
10 10296195525
11 360366843375
12 14054306891625
13 576226582556625
14 29387555710387875
15 1557540452650557375
16 98125048516985114625
17 6378128153604032450625
18 440090842598678239093125

List of values

[1, 1, 3, 15, 135, 1485, 22275, 467775, 10758825, 312005925, 10296195525, 360366843375, 14054306891625, 576226582556625, 29387555710387875, 1557540452650557375, 98125048516985114625, 6378128153604032450625, 440090842598678239093125]

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

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