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 A094376 Least number having exactly n representations as ab+ac+bc with 0 < a < b < c. 5
 1, 11, 23, 41, 47, 59, 71, 116, 119, 131, 164, 425, 191, 236, 239, 446, 335, 419, 311, 404, 431, 584, 647, 524, 479, 1019, 831, 776, 671, 944, 719, 1076, 839, 1004, 959, 1889, 1196, 2099, 1271, 1856, 1151, 1931, 1391, 1676, 1319, 1616, 1751, 3275, 1511 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Note that the Mathematica program computes A094376, A094377 and A094378, but outputs only this sequence. REFERENCES See A025052 LINKS Robert Israel, Table of n, a(n) for n = 0..826 EXAMPLE a(2) = 23 because 23 is the least number with 2 representations: (a,b,c) = (1,2,7) and (1,3,5). MAPLE f:= proc(n) local a, t, s; t:= 0; for a from 1 to floor(sqrt(n/3)) do t:= t + nops(select(s -> s > 2*a and n+a^2 > s^2, numtheory:-divisors(n+a^2))) od; t end proc: N:= 200: # for a(0)..a(N) V:= Array(0..N): count:= 0: for n from 1 while count < N+1 do v:= f(n); if v <= N and V[v] = 0 then count:= count+1; V[v]:= n; fi od: seq(V[i], i=0..N); # Robert Israel, May 05 2021 MATHEMATICA cntMax=10; nSol=Table[{0, 0, 0}, {cntMax+1}]; Do[lim=Ceiling[(n-2)/3]; 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-1}, {b, a+1, 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, 1]], {i, cntMax+1}] CROSSREFS Cf. A000926 (n having no representations), A093669 (n having one representation), A025052, A094377, A094378. Sequence in context: A046440 A232116 A119890 * A086524 A060915 A052034 Adjacent sequences: A094373 A094374 A094375 * A094377 A094378 A094379 KEYWORD nonn AUTHOR T. D. Noe and Robert G. Wilson v, Apr 28 2004 STATUS approved

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Last modified February 21 06:16 EST 2024. Contains 370219 sequences. (Running on oeis4.)