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URL: https://oeis.org/A063943

⇱ A063943 - OEIS

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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
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 * A364905 A362561 A045089
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