A167991 Blocks of size 2n, each with 2n-1 replicas of 2n followed by 2n+1; n=1, 2, 3, ...

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, 18, 18, 18, 18

Offset

1,1

Comments

First differences of A167381.

The sum of the terms in block n is 4*n^2+1 = A053755(n).

Links

Table of n, a(n) for n=1..76.

Example

(2, 3), (4, 4, 4, 5), (6, 6, 6, 6, 6, 7), (8, 8, 8, 8, 8, 8, 8, 9), ...

Mathematica

r[1] = Range[4];
r[n_] := r[n] = Range[r[n-1][[-1]]+1, r[n-1][[-1]] + (2n)^2];
s[n_] := Partition[r[n], Sqrt[Length[r[n]]]][[All, n]];
A167991 = Table[s[n], {n, 1, 9}] // Flatten // Differences (* Jean-François Alcover, Mar 27 2017 *)

Crossrefs

Sequence in context: A349246 A123273 A284359 * A173073 A073425 A087876

Adjacent sequences: A167988 A167989 A167990 * A167992 A167993 A167994

Keyword

nonn,easy

Author

Paul Curtz, Nov 16 2009

Status

approved