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 A066971 a(n) = sigma(sigma(sigma(n))). 6
 1, 7, 8, 15, 28, 56, 24, 60, 24, 56, 56, 120, 60, 168, 168, 63, 56, 120, 96, 252, 104, 112, 168, 480, 63, 252, 234, 360, 195, 336, 104, 210, 224, 360, 224, 248, 168, 480, 360, 546, 252, 728, 224, 504, 480, 336, 224, 504, 186, 255, 336, 260, 360, 1170, 336, 1170 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) = A000203(A000203(A000203(n))) = A000203(A051027(n)) = A051027(A000203(n)). - Jaroslav Krizek, Jul 19 2009 LINKS Harry J. Smith, Table of n, a(n) for n = 1..1000 MATHEMATICA lst={}; Do[AppendTo[lst, DivisorSigma[1, DivisorSigma[1, DivisorSigma[1, n]]]], {n, 5!}]; lst (* Vladimir Joseph Stephan Orlovsky, Mar 11 2009 *) PROG (PARI) for(n=1, 100, print1(sigma(sigma(sigma(n))), ", ")) \\ Lambert Klasen (PARI) { for (n=1, 1000, write("b066971.txt", n, " ", sigma(sigma(sigma(n)))) ) } \\ Harry J. Smith, Apr 12 2010 CROSSREFS Sequence in context: A042001 A020690 A191413 * A084377 A041675 A041098 Adjacent sequences:  A066968 A066969 A066970 * A066972 A066973 A066974 KEYWORD nonn AUTHOR Benoit Cloitre, Jan 26 2002 STATUS approved

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Last modified March 24 01:20 EDT 2019. Contains 321444 sequences. (Running on oeis4.)