A114023 - OEIS

%I #20 Jul 14 2021 12:36:21

%S 4,16,100,144,33489,82369,41088506209,95056905969,196978855329,

%T 4901432910724,6047212155664,26601838343809,247869502464123136

%N Squares of the form semiprime(k) + k-th triangular number.

%C a(14) > 10^18. - _Donovan Johnson_, Jun 04 2013

%o (PARI) lista(nn) = {n = -1; for (i=1, nn, if (bigomega(i) == 2, n++; if (issquare(sq=i + n*(n+1)/2), print1(sq, ", "));););} \\ _Michel Marcus_, Jun 03 2013

%Y Cf. A000217, A001358, A111440, A112662.

%K nonn

%O 1,1

%A _Giovanni Teofilatto_, Feb 01 2006

%E More terms from _Michel Marcus_, Jun 03 2013

%E a(7)-a(13) from _Donovan Johnson_, Jun 04 2013