A378361 - OEIS

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A378361

Octagonal indices of numbers that are both octagonal and octagonal pyramidal.

%I #8 Dec 10 2024 10:25:31

%S 0,1,19,45,6413415,16068720

%N Octagonal indices of numbers that are both octagonal and octagonal pyramidal.

%e 19 is a term because the 19th octagonal number (1045) is also the 10th octagonal pyramidal number.

%Y Cf. A000567 (octagonal numbers), A002414 (octagonal pyramidal numbers).

%Y Cf. A344376.

%K nonn,fini,full,new

%O 1,3

%A _Kelvin Voskuijl_, Nov 23 2024