A117710 - OEIS

A117710

Pentagonal numbers for which the product of the digits is also a pentagonal number.

0, 1, 5, 51, 70, 210, 330, 590, 715, 1001, 1080, 1162, 1520, 1820, 2035, 2380, 2501, 3015, 3290, 3725, 4030, 4510, 5017, 5370, 6112, 6305, 6501, 6700, 6902, 7107, 7740, 8400, 9087, 9560, 9801, 10045, 10292, 10542, 10795, 11051, 11310, 11572, 12105

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..42.

EXAMPLE

715 is in the sequence because it is a pentagonal number and the product of its digits 7*1*5=35 is also a pentagonal number.

MATHEMATICA

pn=Table[n (3 n - 1)/2, {n, 0, 90}] ; Select[pn, MemberQ[pn, Times@@IntegerDigits[#]]&] (* James C. McMahon, Sep 25 2024 *)

CROSSREFS

Cf. A000326, A061380.

Sequence in context: A326738 A322927 A333261 * A064019 A134938 A068540

Adjacent sequences: A117707 A117708 A117709 * A117711 A117712 A117713

KEYWORD

base,nonn,changed

AUTHOR

Luc Stevens (lms022(AT)yahoo.com), Apr 13 2006

STATUS

approved