A074765 Number of composites that are a concatenation nk of n and k for values of k from 1 to n.

0, 2, 2, 2, 4, 5, 5, 7, 8, 6, 10, 11, 10, 13, 12, 13, 15, 16, 14, 18, 18, 17, 20, 20, 22, 22, 22, 25, 26, 26, 26, 29, 26, 30, 28, 31, 32, 33, 32, 34, 35, 35, 37, 39, 40, 39, 42, 44, 42, 44, 48, 46, 49, 44, 50, 48, 49, 49, 53, 52, 52, 56, 53, 57, 57, 60, 60, 60, 61, 61, 65, 63

Offset

1,2

Links

Table of n, a(n) for n=1..72.

Example

a(4) = 2 because we get composites 42 and 44 for 2 values of k, i.e. k = 2, 4.

Crossrefs

Cf. A068696.

Sequence in context: A035659 A008282 A296690 * A029045 A363404 A152432

Adjacent sequences: A074762 A074763 A074764 * A074766 A074767 A074768

Keyword

base,easy,nonn

Author

Jason Earls, Sep 06 2002

Status

approved