0,3

a(n)=n iff n is a square or a pronic (or heteromecic) number of form k(k+1). The sequence interleaves individual squares with 2k copies of each pronic.

Table of n, a(n) for n=0..71.

a(n) = A003059(n)*A000196(n) = n - A038760(n).

a(31)=30 since 6 and 5 are on either side of the square root of 31 and 6*5=30.

Cf. A002378, A053187.

Sequence in context: A118960 A107797 A316788 * A045999 A075569 A062722

Adjacent sequences: A038756 A038757 A038758 * A038760 A038761 A038762

nonn

Henry Bottomley, May 03 2000

approved