1,2

R(i,j)=C(i+j-1,2)+i; cf. A000027, A057061.

Table of n, a(n) for n=1..77.

Sequence in context: A093869 A057431 A179541 * A198380 A152805 A064894

Adjacent sequences: A057057 A057058 A057059 * A057061 A057062 A057063

nonn

Clark Kimberling, Jul 30 2000

approved