id:A061904 - OEIS Search Results

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A061904

Numbers n such that the iterative cycle: n -> sum of digits of n^2 has only one distinct element.

+0
2

1, 3, 6, 9, 10, 12, 15, 18, 21, 30, 39, 45, 48, 51, 60, 90, 100, 102, 105, 111, 120, 150, 180, 201, 210, 249, 300, 318, 321, 348, 351, 390, 450, 480, 501, 510, 549, 600, 900, 1000, 1002, 1005, 1011, 1020, 1050, 1101, 1110, 1149, 1200, 1500, 1761, 1800, 2001 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Since the only numbers invariant under this iteration are 1 and 9, n is contained in this sequence iff the sum of digits of n^2 is 1 or 9.`
	EXAMPLE	`6 -> 3+6 = 9 -> 8+1 = 9 thus 9 is the only element of the iterative cycle of 6. 12 -> 1+4+4 = 9 -> 8+1 = 9 ...`
	CROSSREFS	`Cf. A007953, A004159, A061903 - A061910.` `Sequence in context: A133006 A055264 A113502 this_sequence A111359 A085782 A085780` `Adjacent sequences: A061901 A061902 A061903 this_sequence A061905 A061906 A061907`
	KEYWORD	`nonn,base`
	AUTHOR	`Asher Auel (asher.auel(AT)reed.edu), May 17 2001`

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Last modified September 7 15:23 EDT 2008. Contains 143483 sequences.

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