

A343275


a(n) = 2*n  10^length(n).


1



8, 6, 4, 2, 0, 2, 4, 6, 8, 80, 78, 76, 74, 72, 70, 68, 66, 64, 62, 60, 58, 56, 54, 52, 50, 48, 46, 44, 42, 40, 38, 36, 34, 32, 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40
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OFFSET

1,1


COMMENTS

The plot looks like multiple V shapes. A new V shape occurs for each interval n = 10^k .. 10^(k+1)1, with the bottom of the V at a(5*10^k) = 0.
All terms are even.


LINKS

Rémy Sigrist, Table of n, a(n) for n = 1..9999
Erhan Tezcan, Github Repo includes plots and the code.


FORMULA

a(n) = abs(2*n  10^A055642(n)).
a(10*n) = 10*a(n).


EXAMPLE

n=10 has length 2, so a(10) = 20100 = 80.


PROG

(Python)
def a(n : int) > int:
return abs((n << 1)  (10 ** len(str(n))))
(PARI) a(n) = abs(2*n10^max(1, #digits(n))) \\ Rémy Sigrist, May 30 2021


CROSSREFS

Cf. A055642.
Sequence in context: A263181 A298978 A199151 * A177154 A059631 A333198
Adjacent sequences: A343272 A343273 A343274 * A343276 A343277 A343278


KEYWORD

nonn,base


AUTHOR

Erhan Tezcan, Apr 10 2021


STATUS

approved



