A038511 Composite numbers with smallest prime factor >= 11.

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

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
(GAP) Filtered([11..1000], n->(PowerMod(n, 6, 210)=1 or PowerMod(n, 6, 210)=169) and not IsPrime(n)); # Muniru A Asiru, Nov 24 2018

Crossrefs

Cf. A008364.

Sequence in context: A182776 A080466 A271630 * A285784 A062649 A206288

Adjacent sequences: A038508 A038509 A038510 * A038512 A038513 A038514

Keyword

nonn

Author

Jeff Burch

Status

approved