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%I #34 Dec 21 2024 01:00:41
%S 0,1,1045,5985,123395663059845,774611255177760
%N Numbers that are both octagonal numbers (A000567) and octagonal pyramidal numbers (A002414).
%C Terms correspond to integral points on an elliptic curve, which allows all of them to be found efficiently. - _Max Alekseyev_, Feb 19 2024
%o (PARI) for(k=0, 1e5, if(ispolygonal(m=k*(k+1)*(2*k-1)/2, 8), print1(m", ")))
%Y Intersection of A000567 and A002414.
%Y Cf. A027568, A334012.
%Y Cf. A378361 (octagonal indices), A378918 (octagonal pyramidal indices).
%K nonn,fini,full
%O 1,3
%A _Seiichi Manyama_, May 16 2021
%E Keywords 'fini' and 'full' added by _Max Alekseyev_, Feb 19 2024