The On-Line Encyclopedia of Integer Sequences (OEIS)

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Revision History for A227548

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A227548

Numbers n such that n^3 has n as its middle digits.
(history; published version)

#6 by Ralf Stephan at Thu Aug 01 05:01:02 EDT 2013

STATUS

proposed

approved

#5 by Vincenzo Librandi at Tue Jul 30 05:30:26 EDT 2013

STATUS

editing

proposed

#4 by Vincenzo Librandi at Tue Jul 30 05:30:09 EDT 2013

DATA

1, 50, 56, 60, 90, 4900, 5100, 7500, 7600, 9900, 12500, 499000, 501000, 624000, 625000, 749000, 751000, 875000, 999000, 1249000, 13427757, 49990000, 50010000, 56250000, 62490000

#3 by Joerg Arndt at Tue Jul 30 04:54:53 EDT 2013

KEYWORD

nonn,base,changed

#2 by Vincenzo Librandi at Tue Jul 30 03:32:03 EDT 2013

NAME

allocated for Vincenzo LibrandiNumbers n such that n^3 has n as its middle digits.

DATA

1, 50, 56, 60, 90, 4900, 5100, 7500, 7600, 9900, 12500, 499000, 501000, 624000, 625000, 749000, 751000, 875000, 999000, 1249000, 13427757

OFFSET

1,2

EXAMPLE

a(6)=4900 because 4900^3 = 117649000000 has 4900 as its middle digits.

MATHEMATICA

Do[If[StringPosition[ToString[n^3], ToString[n]][[1, 1]] == (Ceiling[Log[10, n^3]] - Ceiling[Log[10, n]]) / 2 + 1, Print[n]], {n, 0, 10^8}]

CROSSREFS

Cf. A062118.

KEYWORD

allocated

nonn

AUTHOR

Vincenzo Librandi, Jul 30 2013

STATUS

approved

editing

#1 by Vincenzo Librandi at Tue Jul 16 00:47:17 EDT 2013

NAME

allocated for Vincenzo Librandi

KEYWORD

allocated

STATUS

approved