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Zero together with row 9 of the array in A163280.
4

%I #13 Nov 07 2017 11:36:43

%S 0,19,38,51,76,75,114,105,136,162,190,209,264,273,308,345,384,425,468,

%T 513,560,609,660,713,768,825,884,945,1008,1073,1140,1209,1280,1353,

%U 1428,1505,1584,1665,1748,1833,1920,2009,2100,2193,2288,2385,2484,2585,2688

%N Zero together with row 9 of the array in A163280.

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3, -3, 1).

%F Conjecture: a(n) = A028566(n), n > 12. [_R. J. Mathar_, Jul 31 2010]

%p A033676 := proc(n) local dvs; dvs := sort(convert(numtheory[divisors](n), list)) ; op(floor((nops(dvs)+1)/2) , dvs) ; end proc:

%p A163280 := proc(n, k) local r, T ; r := 0 ; for T from k^2 by k do if A033676(T) = k then r := r+1 ; if r = n then return T ; end if; end if; end do: end proc:

%p printf("0, ") ; for n from 1 to 90 do printf("%d, ", A163280(9, n)) ; end do ; # _R. J. Mathar_, Jul 31 2010

%Y Cf. A008578, A161344, A161345, A163280, A164000, A164008, A164010.

%K nonn

%O 0,2

%A _Omar E. Pol_, Aug 08 2009

%E Terms beyond a(12) from _R. J. Mathar_, Jul 31 2010