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.

A097211 a(n) = the number of sets of distinct positive integers with a least common multiple of A025487(n), i.e., A076078(A025487(n)).

Original entry on oeis.org

1, 2, 4, 10, 8, 44, 16, 184, 218, 32, 400, 752, 3748, 64, 3392, 3040, 61064, 128, 27904, 253808, 12224, 64594, 57856, 981520, 256, 226304, 16450240, 49024, 16700300, 954368, 15722528, 512, 1822720, 1055953664, 196352, 4278006328, 15499264
Offset: 1

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Author

Matthew Vandermast, Aug 09 2004

Keywords

Comments

The sequence A025487 contains the least number of each prime signature.
Sequence is a rearrangement of A097210 unless two or more members of A025487 are LCMs of an identical number of sets of distinct positive integers.

Crossrefs

Programs

  • Mathematica
    f[n_] := Block[{d = Divisors[n]}, Plus @@ (MoebiusMu[n/d](2^DivisorSigma[0, d] - 1))]; PrimeExponents[n_] := Flatten[ Table[ # [[2]], {1}] & /@ FactorInteger[n]]; lpe = {}; ln = {1}; Do[pe = Sort[PrimeExponents[n]]; If[ Position[lpe, pe] == {}, AppendTo[lpe, pe]; AppendTo[ln, f[n]]], {n, 1000}]; ln (* Robert G. Wilson v, Aug 14 2004 *)

Extensions

Second comment edited by Matthew Vandermast, Oct 21 2008