A007463 Shifts left under lcm-convolution with itself. (Formerly M1457)

1, 1, 2, 5, 14, 40, 128, 369, 1214, 3516, 12776, 40534, 137404, 463232, 1602348, 5216253, 17753898, 58597316, 212150928, 710453534, 2366853608, 8584498376, 30026959300, 100396304016, 333997297900, 1157269900344, 3852364562536, 13917848281928, 45618032373712

Offset

0,3

References

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Alois P. Heinz, Table of n, a(n) for n = 0..550

M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to arXiv version]

M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]

Maple

a:= proc(n) option remember;
      `if`(n=0, 1, add(ilcm(a(i), a(n-1-i)), i=0..n-1))
    end:
seq(a(n), n=0..30);  # Alois P. Heinz, Jun 22 2012

Mathematica

a[0]=1; a[1]=1; a[n_] := a[n] = Sum[LCM[a[k], a[n-k-1]], {k, 0, n-1}]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Sep 07 2012, after Alois P. Heinz *)

Prog

(PARI) N=66; v=vector(N);  v[1]=1; for(n=2, N, v[n]=sum(k=1, n-1, lcm(v[k], v[n-k])) ); v  \\ Joerg Arndt, Jun 30 2013

Crossrefs

Sequence in context: A151417 A045632 A148321 * A159308 A163189 A243881

Adjacent sequences: A007460 A007461 A007462 * A007464 A007465 A007466

Keyword

nonn,nice,eigen

Author

N. J. A. Sloane

Status

approved