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A167991 Blocks of size 2n, each with 2n-1 replicas of 2n followed by 2n+1; n=1, 2, 3, ... 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 (list; graph; refs; listen; history; text; internal format)
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-Fran├žois Alcover, Mar 27 2017 *)

CROSSREFS

Sequence in context: A145339 A123273 A284359 * A173073 A073425 A087876

Adjacent sequences:  A167988 A167989 A167990 * A167992 A167993 A167994

KEYWORD

nonn,easy

AUTHOR

Paul Curtz, Nov 16 2009

STATUS

approved

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Last modified October 25 01:40 EDT 2021. Contains 348233 sequences. (Running on oeis4.)