%I A137507
%S A137507 1,3,5,7,9,11,13,15,17,19,300,320,340,360,380,400,420,440,460,480,14000,
%T A137507 14200,14400,14600,14800,15000,15200,15400,15600,15800,1060000,1062000,
%U A137507 1064000,1066000,1068000,1070000
%N A137507 100^[n/10] + 2*n*10^[n/10]: inspired by Engel expansion of Pi.
%o A137507 (PARI) a(n) = (n+5 + 10^(floor((n+5)/10)))^2 - (n+5)^2; for (n=1, 30, 
               print1(" "a(n)" ")) \\ changed n+5 to n. - M. F. Hasler, May 02 2008
%o A137507 (PARI) vector(30,n, n--; 2*n*10^(n\10) + 100^(n\10)) \\ - M. F. Hasler, 
               May 02 2008
%Y A137507 Cf. A006784.
%Y A137507 Sequence in context: A143451 A014261 A066640 this_sequence A061808 A143450 
               A005842
%Y A137507 Adjacent sequences: A137504 A137505 A137506 this_sequence A137508 A137509 
               A137510
%K A137507 nonn
%O A137507 0,2
%A A137507 Alexander R. Povolotsky (pevnev(AT)juno.com), Apr 23 2008
%E A137507 Edited by M. F. Hasler (www.univ-ag.fr/~mhasler) and N. J. A. Sloane 
               (njas(AT)research.att.com), May 02 2008