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A173342
Numbers n such that n^7 and a cube are between consecutive squares.
3
2, 3, 498, 2266144, 272585923
OFFSET
1,1
COMMENTS
No other terms < 10^8. The corresponding sequence for n^5 is A173341. Are there ever more than two perfect powers between consecutive squares?
a(6) > 10^10. [From Donovan Johnson, Apr 17 2010]
EXAMPLE
2 is here because 2^7=128 and 5^3=125 are between 11^2=121 and 12^2=144.
3 is here because 3^7=2187 and 13^3=2197 are between 46^2=2116 and 47^2=2209.
498 is here because 498^7 and 1965781^3 are between 2756149047^2 and 2756149048^2.
2266144 is here because 2266144^7 and 674534510965903^3 are between 17518876914709436673663^2 and 17518876914709436673664^2.
MATHEMATICA
t={}; Do[n2=Floor[n^(7/2)]; n3=Round[n^(7/3)]; If[n2^2<n3^3<(n2+1)^2 && n2^2<n^7<(n2+1)^2 && n3^3 != n^7, AppendTo[t, n]], {n, 10^4}]; t
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, Feb 16 2010
EXTENSIONS
a(5) from Donovan Johnson, Apr 17 2010
STATUS
approved