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A087719
Least number m such that the number of numbers k <= m with k > spf(k)^n exceeds the number of numbers with k <= spf(k)^n.
1
15, 27, 57, 135, 345, 927, 2577, 7335, 21225, 62127, 183297, 543735, 1618905, 4832127, 14447217, 43243335, 129533385, 388206927, 1163834337, 3489930135, 10466644665, 31393642527, 94168344657, 282479868135
OFFSET
1,1
COMMENTS
m<a(n): #{k: k>spf(k)^n & 1<=k<=m} <= m/2;
m>=a(n): #{k: k>spf(k)^n & 1<=k<=m} > m/2.
FORMULA
Numbers so far satisfy a(n) = 3^n + 3*2^n + 6. - Ralf Stephan, May 10 2004
Empirical G.f.: 3*x*(5-21*x+20*x^2)/(1-x)/(1-2*x)/(1-3*x). - Colin Barker, Feb 22 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Sep 29 2003
EXTENSIONS
a(14)-a(24) from Giovanni Resta, May 23 2013
STATUS
approved