login
A076601
a(1)=3, a(n_even)=(a(n-1)^2-1)/2; a(n_odd)=a(n-1)+1.
1
3, 4, 5, 12, 13, 84, 85, 3612, 3613, 6526884, 6526885, 21300113901612, 21300113901613, 226847426110843688722000884, 226847426110843688722000885, 25729877366557343481074291996721923093306518970391612, 25729877366557343481074291996721923093306518970391613
OFFSET
1,1
COMMENTS
{3, 4, 5}, {5, 12, 13}, {13, 84, 85}... are sides {a<b<c} of the right triangles, with hypotenuse c=b+1.
MATHEMATICA
Transpose[NestList[{#[[1]]+1, If[EvenQ[#[[1]]+1], (#[[2]]^2-1)/2, #[[2]]+1]}&, {1, 3}, 20]][[2]] (* Harvey P. Dale, May 02 2012 *)
CROSSREFS
Sequence in context: A109350 A239356 A077034 * A372590 A242669 A090829
KEYWORD
easy,nonn
AUTHOR
Zak Seidov, Oct 21 2002
EXTENSIONS
More terms from Harvey P. Dale, May 02 2012
STATUS
approved