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A180169 Sigma(A180162(n)), where A180162(n) is the smallest N such that sigma(N) is an n-th power, or 0 if no such N can be found. 2
1, 3, 4, 8, 1296, 32, 46656, 128, 256, 512, 1024, 362797056, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728, 268435456, 536870912, 1073741824, 2147483648 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Ray Chandler, Table of n, a(n) for n=1..469

FORMULA

Empirical o.g.f.: (-1-1*x+2*x^2-1280*x^4+2560*x^5-46592*x^6+93184*x^7-362795008*x^11+725590016*x^12)/(2*x-1)

Simon Plouffe, Feb. 26 2011.

EXAMPLE

A180162(4)=510 and so A180169(4)=sigma(510)=2^4*3^4.

CROSSREFS

Cf. A065496, A000203, A180162.

Sequence in context: A258372 A096847 A011993 * A154714 A001695 A019676

Adjacent sequences:  A180166 A180167 A180168 * A180170 A180171 A180172

KEYWORD

easy,nonn

AUTHOR

Walter Kehowski, Aug 14 2010

EXTENSIONS

a(23) onwards from Ray Chandler, Aug 20 2010

STATUS

approved

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Last modified March 24 20:02 EDT 2017. Contains 283992 sequences.