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a(n) = 1 + n^4 + n^6.
6

%I #24 Sep 08 2022 08:45:28

%S 3,81,811,4353,16251,47953,120051,266241,538003,1010001,1786203,

%T 3006721,4855371,7567953,11441251,16842753,24221091,34117201,47176203,

%U 64160001,85960603,113614161,148315731,191434753,244531251,309372753,387951931

%N a(n) = 1 + n^4 + n^6.

%H G. C. Greubel, <a href="/A123656/b123656.txt">Table of n, a(n) for n = 1..1000</a>

%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7,-21,35,-35,21,-7,1).

%F a(n) = 1 + n^4 + n^6.

%F G.f.: x*(3 +60*x +307*x^2 +272*x^3 +81*x^4 -4*x^5 +x^6)/(1-x)^7. - _Colin Barker_, May 25 2012

%t Table[1 + n^4 + n^6, {n, 1, 50}] (* _G. C. Greubel_, Oct 17 2017 *)

%t LinearRecurrence[{7,-21,35,-35,21,-7,1},{3,81,811,4353,16251,47953,120051},30] (* _Harvey P. Dale_, May 10 2020 *)

%o (PARI) a(n)=1+n^4+n^6 \\ _Charles R Greathouse IV_, Oct 07 2015

%o (Magma) [1 + n^4 + n^6: n in [1..25]]; // _G. C. Greubel_, Oct 17 2017

%Y Cf. A001358, A002523, A091940, A123177, A123657-A123659.

%K easy,nonn

%O 1,1

%A _Jonathan Vos Post_, Oct 04 2006