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A116173 Numbers n such that n concatenated with n+2 gives the product of two numbers which differ by 6. 9
6752089, 6448802889351008245, 18894512461523256139943105859903480218905, 31958875438439894736354375209245786214798 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also numbers n such that n concatenated with n+7 gives the product of two numbers which differ by 4.

If n+2 and n-5 have the same number of digits, the n is also in A116126, because n//n+2=10^d*n+n+2=k(k+6) then implies a representation n//n-5=10^d*n+n-5 = k(k+6)-7 = (k-1)(k+7). [From R. J. Mathar, Aug 10 2008]

LINKS

Table of n, a(n) for n=1..4.

EXAMPLE

6752089//6752091 = 8217107 * 8217113, where // denotes concatenation.

6752089//6752096 = 8217108 * 8217112.

CROSSREFS

Cf. A116159, A116172, A116174, A116187, A116304.

Cf. A115430, A116205, A116207, A116187, A116337.

Sequence in context: A309385 A022237 A273753 * A088238 A079015 A185435

Adjacent sequences:  A116170 A116171 A116172 * A116174 A116175 A116176

KEYWORD

nonn,base

AUTHOR

Giovanni Resta, Feb 06 2006

EXTENSIONS

Edited by N. J. A. Sloane, Apr 12 2007

STATUS

approved

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Last modified October 17 11:59 EDT 2019. Contains 328110 sequences. (Running on oeis4.)