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A108849 Semiprimes whose digit reversal is a nontrivial power. 1
4, 9, 46, 94, 121, 169, 215, 526, 961, 982, 1042, 1273, 1405, 1843, 2918, 3194, 4069, 4633, 5213, 5221, 6313, 6511, 6937, 8402, 9235, 9481, 9586, 9886, 10201, 10609, 12538, 12769, 14023, 16171, 16327, 16582, 16723, 18085, 18463, 18811, 27845 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Some nonsquare brilliant numbers in the sequence: 70597 = 227*311 (79507 = 43^3), 76121 = 163*467 (12167 = 23^3), 211591 = 457*463 (195112 = 58^3), 291149 = 359*811 (941192 = 98^3) ...

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..14430

EXAMPLE

215 is a term because 215 = 5*43 and 512 = 2^9.

PROG

(PARI) isok(n) = (bigomega(n)==2) && ispower(subst(Polrev(digits(n)), x, 10)); \\ Michel Marcus, Jun 03 2016

CROSSREFS

Cf. A069798.

Sequence in context: A024053 A197970 A048892 * A025558 A298986 A103933

Adjacent sequences:  A108846 A108847 A108848 * A108850 A108851 A108852

KEYWORD

base,nonn

AUTHOR

Jason Earls, Jul 11 2005

STATUS

approved

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Last modified May 16 02:09 EDT 2022. Contains 353687 sequences. (Running on oeis4.)