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A063943 Numbers n such that phi(n) = sigma(n) - sigma(n+1). 1
170, 518, 15416, 16472, 21584, 52744, 140864, 187736, 196318, 318626, 354118, 639286, 828814, 942326, 1333172, 1604018, 3301024, 5240458, 6490678, 7552264, 8040166, 8321326, 9790430, 12237950, 12461834, 14818438, 19012455, 20392318, 22625158, 29201984 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harry J. Smith and Donovan Johnson, Table of n, a(n) for n = 1..100 (first 39 terms from Harry J. Smith)

PROG

(PARI) for(n=1, 30000000, if(eulerphi(n)==sigma(n)-sigma(n+1), print1(n, ", ")))

(PARI) { n=-1; t=0; for (m=1, 10^9, s=t; t=sigma(m + 1); if (eulerphi(m)==s - t, write("b063943.txt", n++, " ", m); if (n==38, break)) ) } [Harry J. Smith, Sep 03 2009]

CROSSREFS

Sequence in context: A043344 A045153 A045041 * A045089 A114078 A031704

Adjacent sequences:  A063940 A063941 A063942 * A063944 A063945 A063946

KEYWORD

nonn

AUTHOR

Jason Earls, Sep 01 2001

EXTENSIONS

More terms from Rick L. Shepherd, Apr 06 2002

Offset corrected by Donovan Johnson, Feb 25 2013

STATUS

approved

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Last modified May 15 05:01 EDT 2021. Contains 343909 sequences. (Running on oeis4.)