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%I #11 Dec 12 2023 08:00:50
%S 1,28,252,757,2044,3528,6813,9632,16380,20440,31752,37296,55261,61544,
%T 86688,95382,131068,137592,183960,192080,257544,260408,335664,340704,
%U 442845,441028,553896,551881,703136,682920,858438,834176,1048572,1008324,1238328,1213632
%N a(0)=1, a(n) = sigma_3(3n).
%F Sum_{k=1..n} a(k) ~ (83*zeta(4)/12) * n^4. - _Amiram Eldar_, Dec 12 2023
%t Join[{1},DivisorSigma[3,3*Range[40]]] (* _Harvey P. Dale_, Feb 02 2012 *)
%o (PARI) a(n) = if(n < 1, 1, sigma(3*n, 3)); \\ _Amiram Eldar_, Dec 12 2023
%Y Trisection of A001158.
%Y Cf. A013662, A045823, A091986, A092342, A092343.
%K nonn,easy
%O 0,2
%A _N. J. A. Sloane_, Mar 20 2004
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