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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.

A090681 Expansion of (sec(x/2)^2 + sech(x/2)^2)/2 in powers of x^4.

Table of values

n a(n)
0 1
1 1
2 31
3 5461
4 3202291
5 4722116521
6 14717667114151
7 86125672563201181
8 868320396104950823611
9 14129659550745551130667441
10 352552873457246307069012458671
11 12942188000689093683411117827763301
12 675618013651758631167025175564066787331
13 48743995308245045290420262686473639399176761

List of values

[1, 1, 31, 5461, 3202291, 4722116521, 14717667114151, 86125672563201181, 868320396104950823611, 14129659550745551130667441, 352552873457246307069012458671, 12942188000689093683411117827763301, 675618013651758631167025175564066787331, 48743995308245045290420262686473639399176761]

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

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