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A130664 a(1)=1. a(n) = a(n-1) + (number of terms from among a(1) through a(n-1) which are factorials). 5
1, 2, 4, 6, 9, 12, 15, 18, 21, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 76, 80, 84, 88, 92, 96, 100, 104, 108, 112, 116, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also this is an irregular array where row n contains the n! consecutive multiples of n starting with n!.

For n >= 1, (a(n), A084555(n)) = (1,1), (2,3), (4,5), (6,8), (9,11), (12,14), ... gives the starting and ending offsets of the n-th permutation in the sequences like A030298 and A030496. Gives also the fixed points of A220662; we have A220662(a(n)) = a(n). - Antti Karttunen, Dec 18 2012

LINKS

A. Karttunen, Rows 1..7 of irregular table, flattened.

FORMULA

a(n) = A084555(n-1) + 1.

EXAMPLE

When interpreted as an irregular table, the rows begin as:

1;

2, 4;

6, 9, 12, 15, 18, 21;

MAPLE

A[1]:= 1:

nextf:= 2!:

m:= 1:

for n from 2 to 100 do

A[n]:= A[n-1]+m;

if A[n] = nextf then

m:= m+1;

nextf:= (m+1)!;

fi;

od:

seq(A[i], i=1..100); # Robert Israel, Apr 28 2016

MATHEMATICA

Table[Range[n!, (n + 1)! - 1, n], {n, 5}] // Flatten (* Michael De Vlieger, Aug 29 2017 *)

PROG

(Scheme): (define (A130664 n) (+ 1 (A084555(- n 1))))

CROSSREFS

Cf. A000142, A084555, A220662.

Sequence in context: A328212 A352191 A256393 * A014011 A064424 A067850

Adjacent sequences: A130661 A130662 A130663 * A130665 A130666 A130667

KEYWORD

easy,nonn

AUTHOR

Leroy Quet, Jun 21 2007

STATUS

approved

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Last modified February 6 18:02 EST 2023. Contains 360111 sequences. (Running on oeis4.)