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Search: id:A077128
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| A077128 |
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Smallest number greater than the previous term which is relatively prime to each of the group of the next n numbers. |
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+0
2
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| 2, 5, 7, 11, 17, 23, 29, 37, 47, 59, 67, 79, 97, 107, 127, 137, 157, 173, 191, 211, 233, 257, 277, 307, 331, 353, 379, 409, 439, 467, 499, 541, 563, 599, 631, 673, 709, 743, 787, 821, 863, 907, 947, 991, 1039, 1087, 1129, 1181, 1229, 1277, 1327, 1381, 1433
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Conjecture : every member is a prime.
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EXAMPLE
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a(6) = 23 is the smallest number coprime to 16,17,1,1,20 and 21.
a(6) = 23 is the smallest number coprime to 16,17,18,19,20 and 21. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 02 2008]
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MAPLE
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A000217 := proc(n) n*(n+1)/2 ; end: A077128 := proc(n) option remember ; local ts, a, goodk, k ; if n = 1 then RETURN(2) ; fi; ts := [seq(A000217(n-1)+i, i=1..n)] ; for a from procname(n-1)+1 do goodk := true ; for k in ts do if gcd(a, k) <> 1 then goodk := false; break ; fi; od: if goodk then RETURN(a) ; fi; od: end: for n from 1 to 100 do printf("%d, ", A077128(n)) ; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 02 2008]
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CROSSREFS
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Cf. A097050. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 02 2008]
Sequence in context: A066408 A142352 A062044 this_sequence A106008 A138244 A019396
Adjacent sequences: A077125 A077126 A077127 this_sequence A077129 A077130 A077131
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Oct 29 2002
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EXTENSIONS
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Extended beyond a(10) by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 02 2008
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