A284359 Double triangle (2*n+2 terms by row). Every row is 2*n + 1 followed by 2*n + 1 times 2*n + 2.

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, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 13, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 15, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 17

Offset

0,2

Comments

In essence the same as A167991. - R. J. Mathar, Mar 27 2017

Links

Table of n, a(n) for n=0..72.

Formula

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

Example

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,
... .
The row sum is A000466(n+1).

Mathematica

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

Prog

(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
(Python)
for n in range(0, 11):
    print([2*n + 2 -(k==1) for k in range(1, 2*n + 3)])
# Indranil Ghosh, Mar 26 2017

Crossrefs

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

Sequence in context: A145339 A349246 A123273 * A167991 A173073 A073425

Adjacent sequences: A284356 A284357 A284358 * A284360 A284361 A284362

Keyword

nonn,tabf

Author

Paul Curtz, Mar 25 2017

Status

approved