The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A019520 a(n) is the concatenation of the first n positive even numbers. 6
 2, 24, 246, 2468, 246810, 24681012, 2468101214, 246810121416, 24681012141618, 2468101214161820, 246810121416182022, 24681012141618202224, 2468101214161820222426, 246810121416182022242628, 24681012141618202224262830, 2468101214161820222426283032 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 REFERENCES H. Ibstedt, A Few Smarandache Sequences, Smarandache Notions Journal, Vol. 8, No. 1-2-3, 1997, 170-183. F. Smarandache, "Collected Papers", Vol. II, Tempus Publ. Hse., Bucharest, Romania, 1996. S. Smarandoiu, Convergence of Smarandache continued fractions, Abstract 96T-11-195, Abstracts Amer. Math. Soc., 17 (No. 4, 1996), 680. LINKS Eric Weisstein's World of Mathematics, Consecutive Number Sequences FORMULA a(n) = a(n-1)*10^floor(log_10(2*n) + 1) + 2*n, with a(1)=2. - Paolo P. Lava, Jan 21 2009 MAPLE P:=proc(i) local a, n; a:=2; print(a); for n from 2 by 1 to i do a:=a*10^floor(evalf((log10(2*n)+1), 100))+2*n; print(a); od; end: P(100); # Paolo P. Lava, Jan 21 2009 MATHEMATICA Table[FromDigits[Flatten[IntegerDigits/@(2Range[n])]], {n, 20}] (* Harvey P. Dale, Mar 24 2013 *) CROSSREFS Sequence in context: A215929 A132596 A099669 * A300400 A187584 A173228 Adjacent sequences:  A019517 A019518 A019519 * A019521 A019522 A019523 KEYWORD base,nonn,easy,less AUTHOR R. Muller EXTENSIONS More terms from Erich Friedman More terms from Harvey P. Dale, Mar 24 2013 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified March 30 16:16 EDT 2020. Contains 333127 sequences. (Running on oeis4.)