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%I A381424 #17 Mar 06 2025 12:53:01
%S A381424 1,31,109,235,409,631,901,1219,1585,1999,2461,2971,3529,4135,4789,
%T A381424 5491,6241,7039,7885,8779,9721,10711,11749,12835,13969,15151,16381,
%U A381424 17659,18985,20359,21781,23251,24769,26335,27949,29611,31321,33079,34885,36739,38641
%N A381424 Truncated hex numbers: a(n) = 24*n^2 + 6*n + 1.
%H A381424 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A381424 a(n) = A003215(3*n) - 6*A000217(n).
%F A381424 a(n) = 6*A007742(n) + 1.
%F A381424 G.f.: (19*x^2+28*x+1)/(1-x)^3.
%e A381424 Illustration of initial terms:
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%e A381424 . 1 31 109
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%t A381424 LinearRecurrence[{3,-3,1},{1,31,109},41] (* _James C. McMahon_, Mar 06 2025 *)
%Y A381424 Cf. A003215, A005892, A007742.
%K A381424 nonn,easy
%O A381424 0,2
%A A381424 _Aaron David Fairbanks_, Feb 23 2025