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A135025
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See Comments lines for definition.
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3
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4, 9, 22, 57, 146, 367, 946, 2507, 6634, 17777, 48522, 133107, 369020, 1028405, 2880288, 8100949
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Let P(n) be the n-th prime. Construct the following sequence:
B(1) = 2
If n>= 2, then if (B(n-1) - P(n) < 0) then B(n) = B(n) + P(n) else B(n) = B(n) - P(n)
Definition: if n>=1, the term B(n) is stationary if it satisfies the inequality B(n-1) < B(n) < B(n+1). Sequence gives the indices n of the stationary terms.
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EXAMPLE
| B(1) = 2
B(2) = 5
B(3) = 0
B(4) = 7
B(5) = 18
B(4) is the first stationary term of B, so 4 is the first term of the sequence.
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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: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 06 2009]
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CROSSREFS
| Cf. A135026.
Sequence in context: A042833 A048654 A122626 * A070713 A060250 A138991
Adjacent sequences: A135022 A135023 A135024 * A135026 A135027 A135028
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KEYWORD
| nonn,more
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AUTHOR
| Lior Deutsch (liorde(AT)gmail.com), Feb 10 2008
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EXTENSIONS
| New term added by Lior Deutsch (liorde(AT)gmail.com), Oct 17 2008
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