A291466 First of the smallest n consecutive sphenic numbers A007304.

30, 230, 1309

Offset

1,1

Comments

Every 4th consecutive number is divisible by 4 = 2*2 and therefore is not sphenic, so a(n) does not exist for n >= 4.

Links

Table of n, a(n) for n=1..3.

Wikipedia, Sphenic number

Example

30 = 2*3*5 is the first spheric number, so a(1) = 30.
The first case of two consecutive sphenic numbers is 230 = 2*5*23 and 231 = 3*7*11, so a(2) = 230.
The first case of three is 1309 = 7*11*17, 1310 = 2*5*131, and 1311 = 3*19*23, so a(3) = 1309.

Crossrefs

Cf. A007304.

Sequence in context: A064241 A080569 A185032 * A246892 A246893 A190068

Adjacent sequences: A291463 A291464 A291465 * A291467 A291468 A291469

Keyword

nonn,fini,full

Author

Jonathan Sondow, Oct 17 2017

Status

approved