A025056 a(n) = position of 3*n^2 in sequence A025051 (numbers of form j*k + k*i + i*j, without repetitions, where 1 <= i <= j <= k).

1, 7, 20, 39, 64, 95, 133, 177, 227, 284, 346, 415, 489, 570, 657, 750, 849, 954, 1065, 1182, 1305, 1434, 1569, 1710, 1857, 2010, 2169, 2334, 2505, 2682, 2865, 3054, 3249, 3450, 3657, 3870, 4089, 4314, 4545, 4782, 5025, 5274, 5529, 5790, 6057, 6330, 6609, 6894

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Crossrefs

Cf. A025051.

Extensions

a(5) onward corrected and more terms from Sean A. Irvine, Aug 05 2019