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 A088550 Primes of the form n^6 + n^5 + n^4 + n^3 + n^2 + n + 1. 14
 7, 127, 1093, 19531, 55987, 5229043, 8108731, 25646167, 321272407, 917087137, 3092313043, 4201025641, 9684836827, 31401724537, 47446779661, 52379047267, 83925549247, 100343116693, 141276239497, 153436090543, 265462278481 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS These numbers, starting with 127, are repunit primes 1111111_n in a base n >= 2, so except 7, they are all Brazilian primes belonging to A085104. In fact, 7 = 111_2 is also Brazilian by this other way. (See Links "Les nombres brésiliens", § V.4 -§ V.5.) A088550 is generated by the bases n present in A100330. - Bernard Schott, Dec 20 2012 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 Bernard Schott, Les nombres brésiliens, Quadrature, no. 76, avril-juin 2010, pages 30-38. Bernard Schott, Les nombres brésiliens, Reprinted from Quadrature, no. 76, avril-juin 2010, pages 30-38, included here with permission from the editors of Quadrature. EXAMPLE a(3) = 1093 = 3^6 + 3^5 + 3^4 + 3^3 + 3^2 + 3 + 1 is prime. MAPLE A088550 := proc(n)     numtheory[cyclotomic](7, A100330(n)) ; end proc: seq(A088550(n), n=1..30) ; MATHEMATICA Select[Table[n^6 + n^5 + n^4 + n^3 + n^2 + n + 1, {n, 100}], PrimeQ] (* Alonso del Arte, Feb 07 2014 *) PROG (PARI) polypn(n, p) = { for(x=1, n, if(p%2, y=2, y=1); for(m=1, p, y=y+x^m; ); if(isprime(y), print1(y", ")); ) } (MAGMA) [a: n in [0..100] | IsPrime(a) where a is 1+n+n^2+n^3+n^4+n^5+n^6] ; // Vincenzo Librandi, Jul 14 2012 CROSSREFS Cf. A085104, A100330. Sequence in context: A061744 A256146 A053716 * A255954 A278791 A064754 Adjacent sequences:  A088547 A088548 A088549 * A088551 A088552 A088553 KEYWORD nonn,easy AUTHOR Cino Hilliard, Nov 17 2003 STATUS approved

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Last modified April 15 07:40 EDT 2021. Contains 342975 sequences. (Running on oeis4.)