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Search: id:A136799
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A136799 Composite runs >2: last term. +0
5
10, 16, 22, 28, 36, 40, 46, 52, 58, 66, 70, 78, 82, 88, 96, 100, 106, 112, 126, 130, 136, 148, 156, 162, 166, 172, 178, 190, 196, 210, 222, 226, 232, 238, 250, 256, 262, 268, 276, 280, 292, 306, 310, 316, 330, 336, 346, 352, 358, 366, 372, 378, 383, 388, 396 (list; graph; listen)
OFFSET

1,1

COMMENT

The program below is useful in testing Grimm's Conjecture, subject of Carlos Rivera's Puzzle 430 in The Prime Puzzles & Problems Connection. Use the program with lines 30 and 70 enabled in the first run, and then disabled with lines 31 and 71 enabled in the second run.

FORMULA

Find sequential runs >2 of composite N. All runs will have an odd number of terms.

a(n) = A025584(n+2) -1 . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 24 2008

EXAMPLE

a(1)=10 because 10 is the last term in a run of three composites beginning with 8 and ending with 10 (8,9,10).

PROGRAM

UBASIC: 10 'puzzle 430 (gap finder) 20 N=1 30 A=1:S=sqrt(N):print N; 31 'A=1:S=N\2:print N; 40 B=N\A 50 if B*A=N and B=prmdiv(B) then print B; 60 A=A+1 70 if A<=sqrt(N) then 40 71 'if A<=N\2 then 40 80 C=C+1:print C 90 N=N+1: if N=prmdiv(N) then C=0:print:stop:goto 90:else 30

CROSSREFS

Cf. A136798 A136800 A136801.

Sequence in context: A129848 A083118 A004261 this_sequence A055987 A109100 A104788

Adjacent sequences: A136796 A136797 A136798 this_sequence A136800 A136801 A136802

KEYWORD

easy,nonn,uned

AUTHOR

Enoch Haga (Enokh(AT)comcast.net), Jan 21 2008

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Last modified December 3 10:07 EST 2008. Contains 151162 sequences.


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