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A318896 Number k such that k and k+1 are the product of exactly four distinct primes. 3
7314, 8294, 8645, 11570, 13629, 13845, 15105, 15554, 16554, 17390, 17654, 18290, 19005, 20405, 20769, 21489, 22010, 22154, 23001, 23114, 23529, 24530, 24765, 24870, 24969, 25346, 26690, 26894, 26961, 27434, 27965, 28105, 29145, 29210, 29414, 29469, 29666, 30414 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This sequence is different from A140078. For example, A140078(4) = 9009 = 3^2 * 7 * 11 * 13 is not a term.

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

EXAMPLE

n | a(n)                    | a(n)+1

--+-------------------------+-------------------------

1 | 7314 = 2 *  3 * 23 * 53 | 7315 = 5 * 7 * 11 *  19

2 | 8294 = 2 * 11 * 13 * 29 | 8295 = 3 * 5 *  7 *  79

3 | 8645 = 5 *  7 * 13 * 19 | 8646 = 2 * 3 * 11 * 131

PROG

(PARI) is(n) = omega(n)==4 && omega(n+1)==4 && bigomega(n)==4 && bigomega(n+1)==4 \\ Felix Fröhlich, Sep 05 2018

(PARI) is(n) = factor(n)[, 2]~ == [1, 1, 1, 1] && factor(n+1)[, 2]~ == [1, 1, 1, 1] \\ David A. Corneth, Sep 06 2018

CROSSREFS

Subsequence of A140078.

Cf. A046386, A052215, A215217, A263990, A318964.

Sequence in context: A116248 A140078 A321504 * A295004 A202167 A235883

Adjacent sequences:  A318893 A318894 A318895 * A318897 A318898 A318899

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Sep 05 2018

STATUS

approved

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Last modified February 16 21:59 EST 2019. Contains 320200 sequences. (Running on oeis4.)