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A063846 Numbers k such that sigma(k) - usigma(k) > 2k. 4
1440, 1800, 2160, 2880, 3024, 3600, 4320, 5040, 5400, 5760, 6048, 6480, 7056, 7200, 7560, 7920, 8064, 8640, 9000, 9072, 9360, 9504, 9720, 10080, 10584, 10800, 11088, 11520, 11880, 12096, 12240, 12600, 12960, 13680, 14040, 14112, 14400, 15120 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 1000 terms from Harry J. Smith)

PROG

(PARI) u(n) = sumdiv(n, d, if(gcd(d, n/d)==1, d));

j=[]; for(n=1, 20000, if(sigma(n)-u(n)>2*n, j=concat(j, n))); j

(PARI) u(n) = sumdiv(n, d, if(gcd(d, n/d)==1, d))

{ n=0; for (m=1, 10^9, if(sigma(m) - u(m) > 2*m, write("b063846.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Sep 01 2009

CROSSREFS

Cf. A034448, A048146, A034683, A064597.

Sequence in context: A081426 A101998 A174277 * A252186 A179691 A078095

Adjacent sequences:  A063843 A063844 A063845 * A063847 A063848 A063849

KEYWORD

easy,nonn

AUTHOR

Jason Earls, Aug 25 2001

STATUS

approved

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Last modified November 18 02:07 EST 2019. Contains 329242 sequences. (Running on oeis4.)