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A019520 a(n) is the concatenation of the first n positive even numbers. 7
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

Table of n, a(n) for n=1..16.

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

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Last modified June 4 03:40 EDT 2020. Contains 334815 sequences. (Running on oeis4.)