id:A137287 - OEIS Search Results

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a(n) = the number 2 written (p(n)-1)/2 times followed with digit 1; p(n) n-th prime number; a(1)=2.

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2, 21, 221, 2221, 222221, 2222221, 222222221, 2222222221, 222222222221, 222222222222221, 2222222222222221, 2222222222222222221, 222222222222222222221, 2222222222222222222221 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`Sum of digits of a(n) = p(n).`
	EXAMPLE	`p(7)=17; (17-1)/2= 8; a(7) = 222222221, 8*"2" concatenated with "1"`
	CROSSREFS	`Cf. A000040, A031974.` `Adjacent sequences: A137284 A137285 A137286 this_sequence A137288 A137289 A137290` `Sequence in context: A037638 A131698 A109684 this_sequence A106412 A058476 A099748`
	KEYWORD	`easy,nonn,base`
	AUTHOR	`Ctibor O. Zizka (ctibor.zizka(AT)seznam.cz), Apr 05 2008`

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Last modified October 11 13:47 EDT 2008. Contains 144830 sequences.

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