A284359 - OEIS

%I #22 Mar 19 2023 23:37:44

%S 1,2,3,4,4,4,5,6,6,6,6,6,7,8,8,8,8,8,8,8,9,10,10,10,10,10,10,10,10,10,

%T 11,12,12,12,12,12,12,12,12,12,12,12,13,14,14,14,14,14,14,14,14,14,14,

%U 14,14,14,15,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,17

%N Double triangle (2*n+2 terms by row). Every row is 2*n + 1 followed by 2*n + 1 times 2*n + 2.

%C In essence the same as A167991. - _R. J. Mathar_, Mar 27 2017

%F a(n) = A167381(n+1) - A167381(n).

%e 1,  2,

%e 3,  4,  4,  4,

%e 5,  6,  6,  6,  6,  6,

%e 7,  8,  8,  8,  8,  8,  8,  8,

%e 9, 10, 10, 10, 10, 10, 10, 10, 10, 10,

%e ... .

%e The row sum is A000466(n+1).

%t Table[2 n + 2 - Boole[k == 1], {n, 0, 8}, {k, 2 n + 2}] // Flatten (* _Michael De Vlieger_, Mar 25 2017 *)

%o (PARI) for(n=0, 10, for(k=1, 2*n + 2, print1(2*n + 2 - (k==1), ", ");); print();) \\ _Indranil Ghosh_, Mar 26 2017, translated from Mathematica code

%o (Python)

%o for n in range(0, 11):

%o     print([2*n + 2 -(k==1) for k in range(1, 2*n + 3)])

%o # _Indranil Ghosh_, Mar 26 2017

%Y Cf. A000466, A005408, A103517 (main diagonal), A167381.

%K nonn,tabf

%O 0,2

%A _Paul Curtz_, Mar 25 2017