A121260 Beginning with a(1)=0, take a(n) to be the smallest number not equal to the product of two consecutive (not distinct) earlier terms.

0, 0, 1, 1, 2, 2, 3, 3, 5, 5, 7, 7, 8, 8, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, 23, 23, 24, 24, 26, 26, 27, 27, 28, 28, 29, 29, 30, 30, 31, 31, 32, 32, 33, 33, 34, 34, 36, 36, 37, 37, 38, 38, 39, 39, 40, 40, 41, 41, 42, 42

Offset: 1

Author

Giovanni Teofilatto, Aug 23 2006

Keywords

• easy
• nonn

Comments

Apparently the definition is: a(1)=0. For even n, a(n)=a(n-1). For odd n, a(n) is the smallest value > a(n-1) which is not equal to some product a(i)*a(i-1) of two consecutive earlier terms. - R. J. Mathar, Jun 21 2021

Crossrefs

Cf. A121229.

Extensions

Offset corrected. - R. J. Mathar, Jun 20 2021