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 A075770 Let u(1)=u(2)=u(3)=1, u(n+3)=(n*u(n)+(n+1)*u(n+1)+(n+2)*u(n+2))/(n+3); sequence gives values of n such that u(n) is an integer. 1

%I

%S 1,2,3,10,14,350,702,817,1053,1405,31426,44770,86766,120118,216918,

%T 284310,343278,347646,426465,511758,767637,1005030,1282398,1483326,

%U 1610510,1930666,2434318,2643990,2883465,3345210,3367430,3420670,3647278

%N Let u(1)=u(2)=u(3)=1, u(n+3)=(n*u(n)+(n+1)*u(n+1)+(n+2)*u(n+2))/(n+3); sequence gives values of n such that u(n) is an integer.

%t a[1] = a[2] = a[3] = 1; a[n_] := a[n] = ((n - 3)*a[n - 3] + (n - 2)*a[n - 2] + (n - 1)*a[n - 1])/n; Flatten[ Position[ Table[a[n], {n, 1, 10^5}], _Integer]]

%K nonn

%O 1,2

%A _Benoit Cloitre_, Oct 09 2002

%E Edited, corrected and extended by _Robert G. Wilson v_, Oct 10 2002

%E a(14) omwards from Lambert Klasen (lambert.klasen(AT)gmx.net), Jul 27 2005

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Last modified October 17 04:09 EDT 2019. Contains 328106 sequences. (Running on oeis4.)