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A374193
a(n) is the smallest number which can be represented as the sum of two nonzero pentagonal pyramidal numbers in exactly n ways, or -1 if no such number exists.
2
2, 1471, 269406
OFFSET
1,1
COMMENTS
There are no further positive terms <= 10^15. - Michael S. Branicky, Jul 01 2024
LINKS
Eric Weisstein's World of Mathematics, Pentagonal Pyramidal Number
EXAMPLE
a(2) = 1471 = 1 + 1470 = 288 + 1183.
CROSSREFS
KEYWORD
nonn,hard,more,bref
AUTHOR
Ilya Gutkovskiy, Jun 30 2024
STATUS
approved