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A063088 a(n) = Sum_{k=1..n} phi(k) - Sum{k=1..n} d(k), where d() is the number of divisors function. 1
0, -1, -1, -2, 0, -2, 2, 2, 5, 5, 13, 11, 21, 23, 27, 30, 44, 44, 60, 62, 70, 76, 96, 96, 113, 121, 135, 141, 167, 167, 195, 205, 221, 233, 253, 256, 290, 304, 324, 332, 370, 374, 414, 428, 446, 464, 508, 514, 553, 567, 595, 613, 663, 673, 709, 725, 757, 781, 837, 841, 899, 925, 955, 980, 1024, 1036, 1100, 1126, 1166 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = A002088(n) - A006218(n). - Michel Marcus, Jun 26 2018

MATHEMATICA

Module[{nn=70, eu, ds}, eu=Accumulate[EulerPhi[Range[nn]]]; ds=Accumulate[ DivisorSigma[ 0, Range[nn]]]; eu-ds] (* Harvey P. Dale, Oct 21 2017 *)

PROG

(PARI) j=[]; for(n=1, 200, a=sum(k=1, n, eulerphi(k)); b=sum(k=1, n, numdiv(k)); j=concat(j, a-b)); j

(PARI) { a=0; for (n=1, 1000, write("b063088.txt", n, " ", a+=eulerphi(n) - numdiv(n)) ) } \\ Harry J. Smith, Aug 17 2009

CROSSREFS

Cf. A002088, A006218.

Sequence in context: A325589 A291308 A207944 * A101276 A103863 A166395

Adjacent sequences:  A063085 A063086 A063087 * A063089 A063090 A063091

KEYWORD

easy,sign

AUTHOR

Jason Earls, Aug 06 2001

STATUS

approved

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Last modified May 20 05:35 EDT 2019. Contains 323418 sequences. (Running on oeis4.)