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A084968 Multiples of 7 coprime to 30. 7
7, 49, 77, 91, 119, 133, 161, 203, 217, 259, 287, 301, 329, 343, 371, 413, 427, 469, 497, 511, 539, 553, 581, 623, 637, 679, 707, 721, 749, 763, 791, 833, 847, 889, 917, 931, 959, 973, 1001, 1043, 1057, 1099, 1127, 1141, 1169, 1183, 1211, 1253, 1267, 1309 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Fourth row of A083140.

LINKS

Table of n, a(n) for n=1..50.

Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,0,1,-1).

FORMULA

GCD( 7k, 30) =1.

G.f.: 7*x*(x^8+6*x^7+4*x^6+2*x^5+4*x^4+2*x^3+4*x^2+6*x+1) / ((x-1)^2*(x+1)*(x^2+1)*(x^4+1)). [Colin Barker, Feb 24 2013]

lim a(n)/n = A038111(4)/A038110(4) = 26.25 as n goes to infinity. - Vladimir Shevelev, Jan 20 2015

EXAMPLE

77 is in the sequence because gcd(77, 30) = 1.

84 is not in the sequence because gcd(84, 3) = 6.

91 is in the sequence because gcd(91, 30) = 1.

MATHEMATICA

7Select[ Range[190], GCD[ #, 2*3*5] == 1 & ]

PROG

(PARI) is(n)=gcd(210, n)==7 \\ Charles R Greathouse IV, Aug 05 2013

CROSSREFS

Subsequence of A008589. Cf. A083140, A007775.

Sequence in context: A083930 A178367 A036132 * A161145 A230655 A008461

Adjacent sequences:  A084965 A084966 A084967 * A084969 A084970 A084971

KEYWORD

nonn,easy

AUTHOR

Robert G. Wilson v, Jun 15 2003

STATUS

approved

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Last modified May 25 08:37 EDT 2017. Contains 287015 sequences.