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A214963 a(0)=a(1)=1, a(n) = least k > a(n-1) such that k*a(n-2) is an oblong number.

%I A214963 #11 May 21 2021 18:38:39
%S A214963 1,1,2,6,10,12,21,35,36,70,112,117,230,368,390,759,763,1290,2244,2292,
%T A214963 3133,3580,4170,5154,5355,7014,7710,9160,9328,11592,19274,22616,27555,
%U A214963 37290,37312,40756,47820,63680,68862,87450,93730,108985,110262,132888,137731,159159
%N A214963 a(0)=a(1)=1, a(n) = least k > a(n-1) such that k*a(n-2) is an oblong number.
%p A214963 isA002378 := proc(n)
%p A214963     if issqr(1+4*n) then
%p A214963         (sqrt(1+4*n)-1) /2 ;
%p A214963         type(%,'integer') ;
%p A214963     else
%p A214963         false;
%p A214963     end if;
%p A214963 end proc:
%p A214963 A214963 := proc(n)
%p A214963     option remember;
%p A214963     local k ;
%p A214963     if n <= 1 then
%p A214963         1;
%p A214963     else
%p A214963         for k from procname(n-1)+1 do
%p A214963             if isA002378(k*procname(n-2)) then
%p A214963                 return k;
%p A214963             end if;
%p A214963         end do:
%p A214963     end if;
%p A214963 end proc: # _R. J. Mathar_, Aug 10 2012
%Y A214963 Cf. A002378.
%K A214963 nonn
%O A214963 0,3
%A A214963 _Alex Ratushnyak_, Aug 03 2012