A147650 First trisection of A061040.
1, 12, 81, 48, 75, 324, 147, 64, 729, 100, 363, 1296, 507, 588, 2025, 768, 289, 2916, 361, 1200, 3969, 1452, 1587, 5184, 1875, 676, 6561, 784, 2523, 8100, 2883, 3072, 9801, 3468, 1225, 11664, 1369, 4332, 13689, 4800, 5043
Offset: 1
Links
- Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,-3,0,0,0,0,0,0,0,0,1).
Programs
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Mathematica
Table[Which[MemberQ[{1, 8}, Mod[n, 9]], n^2, Mod[n, 3] != 0, 3 n^2, True, 9 n^2], {n, 41}] (* Michael De Vlieger, Mar 16 2018 *) -
PARI
a(n) = denominator((n-1)*(n+1)/(9*n^2)); \\ Michel Marcus, Mar 17 2018
Formula
For n >= 1: a(n) = n^2 if n == 1 (mod 9) or == 8 (mod 9). For other n: a(n) = 3*n^2 if n == 1 (mod 3) or == 2 (mod 3), and a(n) = 9*n^2 if n == 0 (mod 3). From the denominator comment above. - Wolfdieter Lang, Mar 16 2018
Extensions
Offset changed from 0 to 1, and extended by Wolfdieter Lang, Mar 16 2018
Comments