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A135025 Let b(1) = 2; and for n>= 2, if b(n-1) < prime(n) then b(n) = b(n-1) + prime(n) otherwise b(n) = b(n-1) - prime(n). The sequence gives the indices n where b(n-1) < b(n) < b(n+1). 5
4, 9, 22, 57, 146, 367, 946, 2507, 6634, 17777, 48522, 133107, 369020, 1028405, 2880288, 8100949, 22877146, 64823569, 184274932, 525282741, 1501215194, 4299836187, 12340952050, 35486796313, 102220582466, 294917666855, 852123981582, 2465458792769 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The b sequence, prefixed by 0, is A008348. The low points in b are 1 less than the terms of the present sequence, and are given in A309226. - N. J. A. Sloane, Aug 31 2019

LINKS

Table of n, a(n) for n=1..28.

EXAMPLE

b(1) = 2

b(2) = 5

b(3) = 0

b(4) = 7

b(5) = 18

b(3) < b(4) < b(5), so 4 is the first term of the sequence.

MAPLE

B := proc(n) option remember ; if n = 1 then 2; else if procname(n-1)-ithprime(n) < 0 then procname(n-1)+ithprime(n) ; else procname(n-1)-ithprime(n) ; fi; fi; end: A135025 := proc(n) option remember ; if n = 1 then 4; else for a from procname(n-1)+1 do if B(a-1) < B(a) and B(a) < B(a+1) then RETURN(a) ; fi; od: fi; end: for n from 1 do printf("%d, \n", A135025(n)) ; od: # R. J. Mathar, Feb 06 2009

CROSSREFS

Cf. A008348, A135026, A309226.

Sequence in context: A318859 A318817 A122626 * A231213 A231338 A257272

Adjacent sequences:  A135022 A135023 A135024 * A135026 A135027 A135028

KEYWORD

nonn,more

AUTHOR

Lior Deutsch (liorde(AT)gmail.com), Feb 10 2008

EXTENSIONS

New term added by Lior Deutsch (liorde(AT)gmail.com), Oct 17 2008

Definition corrected and entry revised by Robert Israel, Michel Marcus, and N. J. A. Sloane, Sep 29 2014

a(17)-a(28) from Giovanni Resta, Oct 02 2019

STATUS

approved

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Last modified June 5 18:48 EDT 2020. Contains 334854 sequences. (Running on oeis4.)