cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A094380 Greatest number having exactly n representations as ab+ac+bc with 1 <= a <= b <= c.

Original entry on oeis.org

462, 142, 742, 862, 2170, 2062, 3502, 2962, 5278, 5413, 7282, 8002, 11302, 11278, 14722, 13918, 18778, 21058, 30178, 30493, 30622, 34318, 47338, 31102, 44902, 43717
Offset: 0

Views

Author

T. D. Noe, Apr 28 2004

Keywords

Comments

Numbers up to 250,000 were checked. Note that the Mathematica program computes A094379, A094380 and A094381, but outputs only this sequence.

Examples

			a(1) = 142 because 142 is the largest number with a unique representation: (a,b,c) = (1,10,12).
		

References

Crossrefs

Cf. A025052 (n having no representations), A093670 (n having one representation), A094379, A094381.

Programs

  • Mathematica
    cntMax=10; nSol=Table[{0, 0, 0}, {cntMax+1}]; 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>cntMax, Break[]]], {a, 1, lim}, {b, a, lim}]; If[cnt<=cntMax, If[nSol[[cnt+1, 1]]==0, nSol[[cnt+1, 1]]=n]; nSol[[cnt+1, 2]]=n; nSol[[cnt+1, 3]]++;], {n, 10000}]; Table[nSol[[i, 2]], {i, cntMax+1}]