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A034957 Divide natural numbers in groups with prime(n) elements and add together. 4
1, 9, 35, 91, 242, 442, 833, 1273, 2024, 3306, 4464, 6586, 8897, 11137, 14288, 18762, 24190, 28670, 35778, 42813, 49275, 59329, 69056, 81702, 98067, 112110, 124836, 140919, 155325, 173568, 210312, 233835, 262903, 285923, 327949, 355001, 393285 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Natural numbers starting from 0,1,2,3,...

LINKS

Hieronymus Fischer, Table of n, a(n) for n = 1..1000

FORMULA

Contribution from Hieronymus Fischer, Sep 27 2012 (Start):

a(n) = sum_{k=(A007504(n-1)+1)..A007504(n)} (k - 1), n>1.

a(n) = (A007504(n) - A007504(n-1))*(A007504(n) + A007504(n-1) - 1)/2, n>1.

a(n) = (A000217(A007504(n) - 1) - A000217(A007504(n-1) - 1)), n>1.

If we define A007504(0):=0, then the formulas above are also true for n=1.

a(n) = A034959(n)/2.

a(n) = A034956(n) - A000040(n).

(End)

EXAMPLE

{0,1} #2 S=1; {2,3,4} #3 S=9; {5,6,7,8,9} #5 S=35; {10,11,12,13,14,15,16} #7 S=91; etc.

CROSSREFS

Cf. A006003, A027441, A034956.

Cf. A046992, A034958-A034960.

Sequence in context: A212099 A212100 A005898 * A180082 A002418 A118414

Adjacent sequences:  A034954 A034955 A034956 * A034958 A034959 A034960

KEYWORD

nonn

AUTHOR

Patrick De Geest, Oct 15 1998.

STATUS

approved

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Last modified October 16 08:03 EDT 2018. Contains 316259 sequences. (Running on oeis4.)