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A068355 Odd n such that sigma(n)*tau(n)>prime(2*n) where sigma(n) is the sum of divisors of n and tau(n) the number of divisors of n = A000005(n). 0
45, 105, 135, 165, 195, 225, 315, 405, 495, 525, 567, 585, 675, 693, 735, 765, 819, 825, 855, 945, 975, 1035, 1071, 1125, 1155, 1197, 1215, 1275, 1287, 1305, 1323, 1365, 1395, 1425, 1449, 1485, 1575, 1617, 1665, 1683, 1701, 1725, 1755, 1785, 1815 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..45.

MATHEMATICA

Select[Range[1, 1901, 2], DivisorSigma[1, #]DivisorSigma[0, #]>Prime[2#]&] (* Harvey P. Dale, Feb 17 2015 *)

PROG

PARI: for(n=1, 2200, if(sigma(n)*numdiv(n)*(1-(-1)^n)/2>prime(2*n), print1(n, ", ")))

CROSSREFS

Sequence in context: A063069 A067828 A144552 * A331190 A332593 A144486

Adjacent sequences:  A068352 A068353 A068354 * A068356 A068357 A068358

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Feb 28 2002

STATUS

approved

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Last modified September 23 22:32 EDT 2020. Contains 337315 sequences. (Running on oeis4.)