A071116 - OEIS

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A071116

Least m such that sigma(n + phi(m)) = sigma(phi(m)).

2049, 81, 383, 67, 7, 25, 11, 103, 17, 271, 29, 159, 1416741, 35 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	COMMENTS	a(15), if it exists, is at least 10^8. The sequence then continues 31, 239, 41, 227, 43, 25, 339, 683, 71, 31, 151, 43, 67, 2897, 89, 59, 61, 81, 97, 35, 131, 110039, 461, 69, 103, 31, 123, 87981, 1941, 53, 197, 311, 213, 41, 161, 141, 187, 67, 143, 167, 161, 89, 353, 479, 339, 124809, 339, 61, 143, 79, 233, 6723723, 313, 724747, 97, 113, 211, 863, 281, 131, 343, 121, 569, 59217, 127, 127, 309, 61, 271, 103, 1329, 359, 229, 79, 299, 89, 911, 264263, 575, 14627, 281, 139, 203, 267, 211, ..., . [From Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 09 2009]
	MATHEMATICA	`a[n_] := For[m=1, True, m++, p=EulerPhi[m]; If[DivisorSigma[1, n+p]==DivisorSigma[1, p], Return[m]]]` `f[n_] := Block[{k = 1}, While[ DivisorSigma[1, n + EulerPhi@k] != DivisorSigma[1, EulerPhi@k], k++ ]; k] [From Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 09 2009]`
	CROSSREFS	`Cf. A000010, A000203.` `Sequence in context: A017303 A017423 A017555 * A060949 A017685 A013959` `Adjacent sequences: A071113 A071114 A071115 * A071117 A071118 A071119`
	KEYWORD	`nonn`
	AUTHOR	`Jason Earls (zevi_35711(AT)yahoo.com), May 27 2002`
	EXTENSIONS	`Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Jun 02 2002` `I extended the search from 7*10^7 to 10^8 Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 09 2009`

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Last modified February 16 21:16 EST 2012. Contains 205971 sequences.