The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A291466

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A291466

First of the smallest n consecutive sphenic numbers A007304.
(history; published version)

#6 by Bruno Berselli at Wed Oct 18 04:44:40 EDT 2017

STATUS

reviewed

approved

#5 by Joerg Arndt at Wed Oct 18 03:00:30 EDT 2017

STATUS

proposed

reviewed

#4 by Jonathan Sondow at Tue Oct 17 18:42:06 EDT 2017

STATUS

editing

proposed

#3 by Jonathan Sondow at Tue Oct 17 18:41:56 EDT 2017

EXAMPLE

30 = 2*3*5 is the first spheric number, so a(1) = 30.

#2 by Jonathan Sondow at Tue Oct 17 18:40:47 EDT 2017

NAME

allocated for Jonathan SondowFirst of the smallest n consecutive sphenic numbers A007304.

DATA

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

Wikipedia, <a href="https://en.wikipedia.org/wiki/Sphenic_number">Sphenic number</a>

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.

KEYWORD

allocated

nonn,fini,full

AUTHOR

Jonathan Sondow, Oct 17 2017

STATUS

approved

editing

#1 by Jonathan Sondow at Thu Aug 24 11:33:41 EDT 2017

NAME

allocated for Jonathan Sondow

KEYWORD

allocated

STATUS

approved

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