cp's OEIS Frontend

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.

A085643 Refines sequence A078812 using permutations and products of exponents on least prime signatures.

Original entry on oeis.org

1, 2, 1, 3, 4, 1, 4, 6, 4, 6, 1, 5, 8, 12, 9, 12, 8, 1, 6, 10, 16, 9, 12, 36, 8, 12, 24, 10, 1, 7, 12, 20, 24, 15, 48, 36, 27, 16, 72, 32, 15, 40, 12, 1, 8, 14, 24, 30, 16, 18, 60, 48, 72, 54, 20, 96, 144, 54, 16, 20, 120, 80, 18, 60, 14, 1
Offset: 1

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Author

Alford Arnold, Aug 15 2003

Keywords

Comments

The shape sequence for this table is A000041. Row sums in the example are A000079, A006906 and A001906.

Examples

			When the signatures (A025487) are listed in A036035 order the number of permutations of the exponents begin
1, 1 1, 1 2 1, 1 2 1 3 1, 1 2 2 3 3 4 1, ... b(n) and the products begin
1, 2 1, 3 2 1, 4 3 4 2 1, 5 4 6 3 4 2 1, ... c(n) thus we can write
1, 2 1, 3 4 1, 4 6 4 6 1, 5 8 12 9 12 8 1, ... a(n) = b(n)*c(n)
		

Crossrefs

Cf. A078812.