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A019520 Concatenate even numbers. 4
2, 24, 246, 2468, 246810, 24681012, 2468101214, 246810121416, 24681012141618, 2468101214161820, 246810121416182022, 24681012141618202224, 2468101214161820222426, 246810121416182022242628 (list; graph; refs; listen; history; 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., Buharest, Romania, 1996.

S. Smarandoiu, Convergence of Smarandache continued fractions, Abstract 96T-11-195, Abstracts Amer. Math. Soc., 17 (No. 4, 1996), 680.

LINKS

M. L. Perez et al., eds., Smarandache Notions Journal

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

FORMULA

a(n)=a(n-1)*10^floor(log10(2*n)+1)+2*n, with a(1)=2. [From Paolo P. Lava (paoloplava(AT)gmail.com), 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); [From Paolo P. Lava (paoloplava(AT)gmail.com), Jan 21 2009]

CROSSREFS

Sequence in context: A143407 A132596 A099669 * A187584 A173228 A061190

Adjacent sequences:  A019517 A019518 A019519 * A019521 A019522 A019523

KEYWORD

base,nonn,easy

AUTHOR

R. Muller

EXTENSIONS

More terms from Erich Friedman (erich.friedman(AT)stetson.edu).

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Last modified February 16 14:05 EST 2012. Contains 205926 sequences.