A134938 Pentagonal numbers that are the sum of a nonzero pentagonal number and a nonzero square in at least one way.

5, 51, 117, 145, 247, 425, 651, 715, 852, 1001, 1247, 1717, 1820, 2147, 2501, 3015, 3151, 4187, 4845, 5017, 5551, 5735, 6305, 6501, 6902, 7107, 7315, 8626, 9087, 9322, 9801, 11051, 11572, 12105, 14065, 14357, 15251, 16801, 17767, 18095, 18426, 18760, 19780

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000 (replaces erroneous b-file from Harvey P. Dale)

Maple

pent:= n -> n*(3*n-1)/2:
filter:= proc(n) local x, y, S;
   S:= [isolve(pent(x) + y^2 = n)];
   ormap(t -> subs(t, x) > 0 and subs(t, y) > 0, S)
end proc:
select(filter, map(pent, [$1 .. 30])); # Robert Israel, Jul 21 2025

Crossrefs

Sequence in context: A333261 A117710 A064019 * A068540 A208997 A041043

Adjacent sequences: A134935 A134936 A134937 * A134939 A134940 A134941

Keyword

nonn

Author

Jonathan Vos Post, Jan 21 2008

Extensions

Added more terms from b-file. - David Radcliffe, Jul 21 2025

Status

approved