OFFSET
1,2
FORMULA
a(n) = (3*t+2-t*(-1)^(t-1))/2-(1+(-1)^t)*(j-1)/2+(1-(-1)^t)*(j-1)/2, where j = (t*t+3*t+4)/2-n, t=floor((-1+sqrt(8*n-7))/2). - Boris Putievskiy, Jan 30 2013
EXAMPLE
1
3 2
3 4 5
7 6 5 4
5 6 7 8 9
11 10 9 8 7 6
...
MAPLE
for n from 1 to 14 do if n mod 2 = 1 then print(seq(k, k=n..2*n-1)) else print(seq(2*n-k, k=1..n)) fi od; # yields sequence in triangular form # Emeric Deutsch, Jan 26 2006
CROSSREFS
KEYWORD
AUTHOR
Amarnath Murthy, Nov 15 2005
EXTENSIONS
More terms from Emeric Deutsch, Jan 26 2006
STATUS
approved