A137895 - OEIS

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A137895

Products of two or more consecutive numbers that do not have prime gaps in their factorizations.

2, 6, 12, 24, 30, 60, 72, 90, 120, 210, 240, 360, 420, 600, 720, 840, 1260, 1680, 2520, 3360, 5040, 6480, 6720, 9240, 15120, 15750, 20160, 30240, 40320, 50400, 55440, 60480, 117600, 147840, 151200, 166320, 181440, 194040, 240240, 291060, 332640

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Intersection of A045619 and A073491; A000142 is a subsequence apart from initial terms.

LINKS

David A. Corneth, Table of n, a(n) for n = 1..193

EXAMPLE

a(10) = 210 = 2 * 3 * 5 * 7 = 5 * (5+1) * (5+2);

a(11) = 240 = 2^4 * 3 * 5 = 15 * (15+1);

a(12) = 360 = 2^3 * 3^2 * 5 = 3 * (3+1) * (3+2) * (3+3);

a(13) = 420 = 2^2 * 3 * 5 * 7 = 20 * (20+1);

a(14) = 600 = 2^3 * 3 * 5^2 = 24 * (24+1);

a(15) = 720 = 2^4 * 3^2 * 5 = 6!.

CROSSREFS

Subsequence of A055932.

Cf. A045619, A073491, A000142.

Sequence in context: A244043 A058868 A129314 * A194096 A099993 A011778

Adjacent sequences: A137892 A137893 A137894 * A137896 A137897 A137898

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Feb 20 2008

STATUS

approved