A086673 Number of right-truncatable semiprimes <= n.

0, 0, 0, 1, 1, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 10, 11, 12, 12, 12, 12

Offset

1,6

Links

Table of n, a(n) for n=1..98.

I. O. Angell and H. J. Godwin, On Truncatable Primes, Math. Comput. 31, 265-267, 1977.

Eric Weisstein's World of Mathematics, Semiprime

Index entries for sequences related to truncatable primes

Crossrefs

Cf. A085733, A001358.

Sequence in context: A192688 A156752 A345073 * A101787 A343607 A269024

Adjacent sequences: A086670 A086671 A086672 * A086674 A086675 A086676

Keyword

nonn

Author

Reinhard Zumkeller, Jul 27 2003

Status

approved