A090112 a(n)=pi(n)*[pi(n)-pi(n-2)] where pi(n)=A000720(n).

0, 1, 4, 2, 3, 3, 4, 4, 0, 0, 5, 5, 6, 6, 0, 0, 7, 7, 8, 8, 0, 0, 9, 9, 0, 0, 0, 0, 10, 10, 11, 11, 0, 0, 0, 0, 12, 12, 0, 0, 13, 13, 14, 14, 0, 0, 15, 15, 0, 0, 0, 0, 16, 16, 0, 0, 0, 0, 17, 17, 18, 18, 0, 0, 0, 0, 19, 19, 0, 0, 20, 20, 21, 21, 0, 0, 0, 0, 22, 22, 0, 0, 23, 23, 0, 0, 0, 0, 24, 24

Offset

1,3

Links

Table of n, a(n) for n=1..90.

Crossrefs

Cf. A049084, A000720, A010051, A000027, A090113.

Sequence in context: A136626 A079623 A177864 * A226087 A118945 A016692

Adjacent sequences: A090109 A090110 A090111 * A090113 A090114 A090115

Keyword

nonn

Author

Labos Elemer, Jan 08 2004

Status

approved