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 A143231 a(n) = A000010(n) * A002088(n). 2
 1, 2, 8, 12, 40, 24, 108, 88, 168, 128, 420, 184, 696, 384, 576, 640, 1536, 612, 2160, 1024, 1680, 1500, 3784, 1440, 4000, 2544, 4140, 2904, 7560, 2224, 9240, 5184, 6880, 5760, 9216, 4752, 15552, 8100, 11376, 7840, 21200, 6504, 24528, 12080, 15072, 14300 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Nathaniel Johnston, Table of n, a(n) for n = 1..2500 FORMULA a(n) = A000010(n) * A002088(n). Equals row sums of triangle A143230. EXAMPLE a(5) = 40 = A000010(5) * A002088(5) = 4 * 10. a(5) = 40 = sum of row 5 terms of triangle A143230: (4 + 4 + 8 + 8 + 16). MAPLE with(numtheory): a := proc(n) return phi(n)*add(phi(k), k=1..n): end: seq(a(n), n=1..46); # Nathaniel Johnston, Jun 26 2011 PROG (PARI) a(n)=sum(k=1, n, eulerphi(k))*eulerphi(n) \\ Charles R Greathouse IV, Feb 21 2013 CROSSREFS Cf. A000010, A002088, A143230. Sequence in context: A176961 A078541 A285551 * A104039 A135443 A280092 Adjacent sequences: A143228 A143229 A143230 * A143232 A143233 A143234 KEYWORD nonn AUTHOR Gary W. Adamson, Jul 31 2008 EXTENSIONS Terms after a(14) from Nathaniel Johnston, Jun 26 2011 STATUS approved

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Last modified June 13 22:21 EDT 2024. Contains 373391 sequences. (Running on oeis4.)