%I A028992
%S A028992 24,46,154,204,396,474,750,856,1216,1350,1794,1956,2484,2674,3286,
%T A028992 3504,4200,4446,5226,5500,6364,6666,7614,7944,8976,9334,10450,10836,
%U A028992 12036,12450,13734,14176,15544,16014,17466,17964,19500,20026,21646
%N A028992 Even 9-gonal (or enneagonal) numbers.
%H A028992 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               NonagonalNumber.html">Source</a>
%F A028992 (1/2)[28n^2 + 60n + 33 + (14n+15)(-1)^n].
%Y A028992 Cf. A001106.
%Y A028992 Sequence in context: A000496 A063323 A154590 this_sequence A040552 A098427 
               A105651
%Y A028992 Adjacent sequences: A028989 A028990 A028991 this_sequence A028993 A028994 
               A028995
%K A028992 nonn
%O A028992 1,1
%A A028992 Patrick De Geest (pdg(AT)worldofnumbers.com)