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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.

User: Radaev Nikita

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A340536 Digital root of 2*n^2.

Original entry on oeis.org

2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9
Offset: 1

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Author

Radaev Nikita, Jan 10 2021

Keywords

Comments

Period 9: repeat [2, 8, 9, 5, 5, 9, 8, 2, 9].
This sequence is also right if digital root of factor in "2*n^2" is 2 (for example, "11*n^2", "20*n^2", "29*n^2", etc.)

Examples

			For n=5, 2*5^2 = 50 and digital root is 5, so a(5) = 5.

Links

Crossrefs

Cf. A001105, A010888, A056992.

Programs

Formula

a(n) = A010888(A001105(n)).

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