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A117710
Pentagonal numbers for which the product of the digits is also a pentagonal number.
1
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
OFFSET
0,3
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
Sequence in context: A326738 A322927 A333261 * A064019 A134938 A068540
KEYWORD
base,nonn
AUTHOR
Luc Stevens (lms022(AT)yahoo.com), Apr 13 2006
STATUS
approved