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A153848
Repeat 21.
1
21, 2121, 212121, 21212121, 2121212121, 212121212121, 21212121212121, 2121212121212121, 212121212121212121, 21212121212121212121, 2121212121212121212121, 212121212121212121212121, 21212121212121212121212121, 2121212121212121212121212121
OFFSET
1,1
FORMULA
a(n) = (10^(2*n)-1)*21/99.
MAPLE
a:= n-> parse(cat(21$n)):
seq(a(n), n=1..20); # Alois P. Heinz, Jun 16 2021
PROG
(PARI) g2(n) = (10^(2*n)-1)*1*21/99 for(x=1, 25, print1(g2(x), ", "))
CROSSREFS
Cf. A177090.
Sequence in context: A265175 A300577 A304643 * A221771 A007593 A219104
KEYWORD
nonn,easy
AUTHOR
Cino Hilliard, Jan 02 2009
STATUS
approved