A025064 Position of numbers of form 3*n^2 in A025060 (numbers of form j*k + k*i + i*j, where 1 <=i < j < k).

8, 43, 70, 105, 146, 194, 248, 307, 374, 448, 528, 615, 707, 805, 910, 1021, 1138, 1260, 1388, 1523, 1664, 1810, 1963, 2122, 2287, 2458, 2635, 2818, 3007, 3202, 3403, 3610, 3823, 4042, 4267, 4498, 4735, 4978

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Programs

Maple

N:= 10000: # to get positions of all 3*n^2 <= N
B:= sort(convert({seq(seq(seq(i*j + j*k + i*k, i=1..min(j-1, (N-j*k)/(j+k))),j=2..min(k-1,(N-k)/(1+k))),k=3..(N-2)/3)},list)):
count:= 1:
for n from 1 to floor(sqrt(N/3)) do
  if member(3*n^2,B,A[count]) then count:= count+1 fi
od:
seq(A[i],i=1..count-1); # Robert Israel, Sep 06 2016

Formula

It is conjectured that A000926 ends at 1848, in which case a(n) = 3*n^2+18*n-38 for all n >= 22. - Robert Israel, Sep 06 2016

Extensions

More terms and a(4)-a(7) corrected by Gionata Neri, Sep 06 2016