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A115708 Semiprimes (A001358) whose digit reversal is a pentagonal number (A000326). 1
10, 15, 21, 22, 235, 287, 517, 529, 671, 1513, 1555, 2611, 5137, 5331, 6241, 7017, 7171, 7421, 7597, 7814, 10078, 10913, 15011, 15094, 15214, 15251, 20395, 20603, 21542, 23129, 24501, 24873, 25157, 26851, 27161, 51998, 53297, 54989, 55551 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..39.

EXAMPLE

235=5*47 is semiprime and 532 is the 19th pentagonal number.

CROSSREFS

Cf. A000326, A001358, A115709.

Sequence in context: A105156 A108614 A336548 * A068992 A325901 A098564

Adjacent sequences:  A115705 A115706 A115707 * A115709 A115710 A115711

KEYWORD

nonn,base

AUTHOR

Giovanni Resta, Jan 31 2006

STATUS

approved

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Last modified December 5 10:11 EST 2021. Contains 349543 sequences. (Running on oeis4.)