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A093670 Numbers having a unique representation as ab+ac+bc, with 1 <= a <= b <= c. 4
3, 5, 7, 8, 9, 12, 13, 14, 16, 25, 28, 34, 37, 46, 82, 142 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Are there more terms?

REFERENCES

See A025052

LINKS

Table of n, a(n) for n=1..16.

EXAMPLE

25 is on the list because 25 = 1*1 + 1*12 + 1*12.

MATHEMATICA

oneSol={}; Do[lim=Ceiling[(n-1)/2]; cnt=0; Do[If[n>a*b && Mod[n-a*b, a+b]==0 && Quotient[n-a*b, a+b]>=b, cnt++; If[cnt>1, Break[]]], {a, 1, lim}, {b, a, lim}]; If[cnt==1, AppendTo[oneSol, n]], {n, 10000}]; oneSol

CROSSREFS

Cf. A025052 (numbers not of the form ab+ac+bc, 1<=a<=b<=c).

Sequence in context: A229838 A191257 A120212 * A185011 A175144 A183054

Adjacent sequences:  A093667 A093668 A093669 * A093671 A093672 A093673

KEYWORD

nonn

AUTHOR

T. D. Noe, Apr 08 2004

STATUS

approved

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Last modified July 16 04:26 EDT 2019. Contains 325064 sequences. (Running on oeis4.)