A395932 - OEIS

%I #23 Jun 13 2026 06:50:26

%S 1,1,6,50,600,8028,118124,2239344,44339040,924118272,20313753096,

%T 544873631616,14920424467200,420930757866240,12283618766690304,

%U 371384787345228000,13230401127979507200,476868219163709184000,17514571789229243904000,657990721584550597939200,25335867498073940938060800

%N Main diagonal of A396981.

%o (PARI) A002024(n) = (sqrtint(8*n-7)+1)\2

%o a(n) = my(v1 = vector(A002024(n+1), i, 0), v2 = vector(n+1, i, 0), v3); v1[1] = n; v2[1] = 1; for(i=2, #v1, v1[i] = v1[i-1] - A002024(v1[i-1])); v1 = Vecrev(v1); for(i=2, #v1, v3 = vector(n+1, i, 0); v3[1] = 1; A = v1[i] - v1[i-1]; for(j=1, n, v3[j+1] = v2[j+1] + (j+A-1)*v3[j]); v2 = v3); v2[n+1]

%Y Cf. A002024, A396981.

%K nonn

%O 0,3

%A _Mikhail Kurkov_, Jun 12 2026