OFFSET
0,2
COMMENTS
The Granvik array of A172119 is here written in "square": 1 :: 1 :: 1 :: 1 :: 1 :: 1 :: 1 :: 1 :: 1 :: 1 // 1 :: 2 :: 2 :: 2 :: 2 :: 2 :: 2 :: 2 :: 2 :: 2 // 1 :: 3 :: 4 :: 4 :: 4 :: 4 :: 4 :: 4 :: 4 :: 4 // 1 :: 4 :: 7 :: 8 :: 8 :: 8 :: 8 :: 8 :: 8 :: 8 // This sequence gives the third diagonal under the main diagonal.
LINKS
FORMULA
a(n) = 8*2^n-12, n>=2. - R. J. Mathar, Apr 20 2011
EXAMPLE
From 1 + 5*z + 20*z^2 + 52*z^3 + 116*z^4 + 244*z^5 + 500*z^6 + O(z^7) we get a(6)=500.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Richard Choulet, Feb 07 2010
STATUS
approved