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A181800 Powerful numbers that are the least integer of their prime signature. 15
1, 4, 8, 16, 32, 36, 64, 72, 128, 144, 216, 256, 288, 432, 512, 576, 864, 900, 1024, 1152, 1296, 1728, 1800, 2048, 2304, 2592, 3456, 3600, 4096, 4608, 5184, 5400, 6912, 7200, 7776, 8192, 9216, 10368, 10800, 13824, 14400, 15552, 16384, 18432, 20736, 21600, 27000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Apart from 1, all terms in this sequence are multiples of 4. - Charles R Greathouse IV, Dec 13 2016

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..1000

FORMULA

Intersection of A001694 and A025487.

PROG

(PARI) is(n)=if(n<4, return(n==1)); my(f=factor(n)); vecmin(f[, 2])>1 && f[, 1]~ == primes(#f~) && f[, 2] == vecsort(f[, 2], , 4) \\ Charles R Greathouse IV, Sep 14 2015

CROSSREFS

Cf. A001694 (powerful numbers), A025487 (least integer of each prime signature)

Sequence in context: A125626 A141031 A061011 * A075090 A283052 A088259

Adjacent sequences:  A181797 A181798 A181799 * A181801 A181802 A181803

KEYWORD

nonn

AUTHOR

Matthew Vandermast, Dec 02 2010

STATUS

approved

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Last modified June 28 17:14 EDT 2017. Contains 288839 sequences.