1,2
565187=P(614) and 781565=P(722), where P(k)=k(3k-1)/2 is the k-th pentagonal number.
Cf. A000326, A061455, A061457.
Sequence in context: A129437 A048252 A066866 this_sequence A066865 A005632 A002069
Adjacent sequences: A115654 A115655 A115656 this_sequence A115658 A115659 A115660
base,nonn
Giovanni Resta (g.resta(AT)iit.cnr.it), Jan 28 2006
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