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%I #13 Aug 31 2024 05:34:49
%S 2,3,4,6,7,8,9,10,11,13,14,15,16,17,18,19,20,21,23,24,25,26,27,28,29,
%T 30,31,32,33,34,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,52,53,54,
%U 55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,93
%N Complement of the pentagonal numbers.
%F a(n) = n + floor(1/2+(2n/3)^(1/2)).
%F a(n) = n + A111651(n). - _Kevin Ryde_, Aug 31 2024
%e The pentagonal numbers A000326 = (1,5,12,22,35,...), so that this sequence = (2,3,4,6,7,8,9,10,11,13,14,...).
%t Table[n+Floor[1/2+(2n/3)^(1/2)], {n,100}]
%o (PARI) a(n) = n + sqrtint(24*n)\/6; \\ _Kevin Ryde_, Aug 31 2024
%Y Cf. A000326, A111651.
%K nonn,easy,changed
%O 1,1
%A _Clark Kimberling_, Jan 01 2011
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