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A137287 a(n) = the number 2 written (p(n)-1)/2 times followed with digit 1; p(n) n-th prime number; a(1)=2. 0
2, 21, 221, 2221, 222221, 2222221, 222222221, 2222222221, 222222222221, 222222222222221, 2222222222222221, 2222222222222222221, 222222222222222222221, 2222222222222222222221 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Sum of digits of a(n) = p(n).

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

p(7)=17; (17-1)/2= 8; a(7) = 222222221, 8*"2" concatenated with "1"

CROSSREFS

Cf. A000040, A031974.

Sequence in context: A163068 A109684 A292134 * A155872 A323478 A106412

Adjacent sequences:  A137284 A137285 A137286 * A137288 A137289 A137290

KEYWORD

easy,nonn,base

AUTHOR

Ctibor O. Zizka, Apr 05 2008

STATUS

approved

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Last modified April 21 07:26 EDT 2021. Contains 343146 sequences. (Running on oeis4.)