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%I #10 Mar 06 2020 08:11:11
%S 205427,210552,230102,269712,333802,346977,354537,384802,397892,
%T 416677,420077,426622,448552,470902,471927,478302,509752,520852,
%U 563772,566177,569507,571377,575202,580302,586102,590162,599847,610052,616552,618263,635552,646177,647947
%N Numbers which can be written in exactly five ways as a sum of two distinct nonzero pentagonal numbers.
%e 205427 = P(234) + P(287) = P(201) + P(311) = P(166) + P(331) = P(56) + P(366) = P(49) + P(367), where P(n) is the n-th pentagonal number (A000326).
%o (PARI) is(k) = sum(i=1, sqrt(1+12*k)\6, sqrt(1+24*k+12*i-36*i*i)%6==5) == 5; \\ _Jinyuan Wang_, Mar 06 2020
%Y Cf. A000326, A332988, A332989, A333011, A333012, A333013, A333014.
%K nonn
%O 1,1
%A _Olivier Gérard_, Mar 05 2020
%E More terms from _Jinyuan Wang_, Mar 06 2020