OFFSET
0,3
COMMENTS
For n > 2, a(n) and a(n-1) share at least one prime factor.
Shows how many patterns can be created with 1-color thread while sewing on a button with buttonholes located on the vertices of a convex n-gon. - Ivan N. Ianakiev, Feb 09 2012
REFERENCES
Masha Gessen, Perfect Rigor, A Genius and the Mathematical Breakthrough of the Century, Houghton Mifflin Harcourt, 2009, page 38.
LINKS
Muniru A Asiru, Table of n, a(n) for n = 0..80
FORMULA
a(n) = A006125(n+1) - 1. - Zerinvary Lajos, Jun 12 2007
MAPLE
seq(2^(binomial(n+1, 2))-1, n=0..12); # Zerinvary Lajos, Jun 12 2007
MATHEMATICA
FoldList[Times, 2^Range[0, 20]]-1 (* Harvey P. Dale, Sep 09 2015 *)
2^Accumulate[Range[0, 20]]-1 (* Harvey P. Dale, Jun 03 2019 *)
PROG
(GAP) List([-1..15], n->2^(Binomial(2+n, n))-1); # Muniru A Asiru, Feb 21 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Marco Matosic, Dec 29 2006
EXTENSIONS
Corrected and extended by Harvey P. Dale, Sep 09 2015
STATUS
approved