id:A028837 - OEIS Search Results

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Iterated sum of digits of n is a square.

+0
3

1, 4, 9, 10, 13, 18, 19, 22, 27, 28, 31, 36, 37, 40, 45, 46, 49, 54, 55, 58, 63, 64, 67, 72, 73, 76, 81, 82, 85, 90, 91, 94, 99, 100, 103, 108, 109, 112, 117, 118, 121, 126, 127, 130, 135, 136, 139, 144, 145, 148, 153, 154, 157, 162, 163, 166, 171, 172, 175, 180 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`a(n) = a(n-3)+9. If n is a multiple of 3 then a(n) = 3n, otherwise a(n) = 3n-2. Numbers of form {0, 1, 4} modulo 9 - Henry Bottomley (se16(AT)btinternet.com), Jun 30 2000`
	EXAMPLE	`E.g. 58 -> 5+8 = 13 -> 1+3 = 4 is a square.`
	CROSSREFS	`Cf. A010888, A028839, A028845.` `Sequence in context: A086390 A038029 A020672 this_sequence A028839 A140292 A010426` `Adjacent sequences: A028834 A028835 A028836 this_sequence A028838 A028839 A028840`
	KEYWORD	`nonn,base`
	AUTHOR	`njas`
	EXTENSIONS	`More terms from Patrick De Geest (pdg(AT)worldofnumbers.com), Jun 15 1999.`

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Last modified July 25 02:12 EDT 2008. Contains 142294 sequences.

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