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A038511 Composite numbers with smallest prime factor >= 11. 3
121, 143, 169, 187, 209, 221, 247, 253, 289, 299, 319, 323, 341, 361, 377, 391, 403, 407, 437, 451, 473, 481, 493, 517, 527, 529, 533, 551, 559, 583, 589, 611, 629, 649, 667, 671, 689, 697, 703, 713, 731, 737, 767, 779, 781, 793, 799, 803, 817, 841, 851 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Composite n such that n^6 is congruent to {1, 169} mod 210. All primes > 7 satisfy this condition. [Gary Detlefs, Dec 09 2012]

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

FORMULA

a(n) ~ 4.375n. - Charles R Greathouse IV, Dec 10 2012

MAPLE

for n from 1 to 1000 do if (n^6 mod 210 = 1 or n^6 mod 210 = 169) and not isprime(n) then print(n) fi od; # Gary Detlefs, Dec 09 2012

MATHEMATICA

Select[Range[1000], Not[PrimeQ[#]] && FactorInteger[#][[1, 1]] > 7 &] (* Alonso del Arte, Dec 09 2012 *)

PROG

(PARI) is(n)=gcd(210, n)==1 && !isprime(n) \\ Charles R Greathouse IV, Dec 10 2012

CROSSREFS

Sequence in context: A020253 A182776 A080466 * A062649 A206288 A242372

Adjacent sequences:  A038508 A038509 A038510 * A038512 A038513 A038514

KEYWORD

nonn

AUTHOR

Jeff Burch

STATUS

approved

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Last modified October 25 17:33 EDT 2014. Contains 248557 sequences.