The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A198244 Primes of the form k^10 + k^9 + k^8 + k^7 + k^6 + k^5 + k^4 + k^3 + k^2 + k + 1 where k is nonprime. 2
 11, 10778947368421, 17513875027111, 610851724137931, 614910264406779661, 22390512687494871811, 22793803793211153712637, 79905927161140977116221, 184251916941751188170917, 319465039747605973452001, 1311848376806967295019263, 1918542715220370688851293 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Subsequence of A060885. From Bernard Schott, Nov 01 2019: (Start) These are the primes associated with the terms k of A308238. A162861 = A286301 Union {this sequence}. The numbers of this sequence R_11 = 11111111111_k with k > 1 are Brazilian primes, so belong to A085104. (End) LINKS Chai Wah Wu, Table of n, a(n) for n = 1..1658 FORMULA {A060885(A018252(n)) which are in A000040}. EXAMPLE 10778947368421 is in the sequence since 10778947368421 = 20^10 + 20^9 + 20^8 + 20^7 + 20^6 + 20^5 + 20^4 + 20^3 + 20^2 + 20 + 1, 20 is not prime, and 10778947368421 is prime. MAPLE f:= proc(n) local p, j; if isprime(n) then return NULL fi; p:= add(n^j, j=0..10); if isprime(p) then p else NULL fi end proc: map(f, [\$1..1000]); # Robert Israel, Nov 19 2014 PROG (Python) from sympy import isprime A198244_list, m = [], [3628800, -15966720, 28828800, -27442800, 14707440, -4379760, 665808, -42240, 682, 0, 1] for n in range(1, 10**4): ....for i in range(10): ........m[i+1]+= m[i] ....if not isprime(n) and isprime(m[-1]): ........A198244_list.append(m[-1]) # Chai Wah Wu, Nov 09 2014 (Magma) [a: n in [0..500] | not IsPrime(n) and IsPrime(a) where a is (n^10+n^9+n^8+n^7+n^6+n^5+n^4+n^3+n^2+n+1)]; // Vincenzo Librandi, Nov 09 2014 (PARI) forcomposite(n=0, 10^3, my(t=sum(k=0, 10, n^k)); if(isprime(t), print1(t, ", "))); \\ Joerg Arndt, Nov 10 2014 CROSSREFS Cf. A162861, A000040, A088548, A192321, A102909, A060885, A308238. Similar to A185632 (k^2+ ...), A193366 (k^4+ ...), A194194 (k^6+ ...). Sequence in context: A213647 A072218 A046844 * A066953 A213645 A257139 Adjacent sequences: A198241 A198242 A198243 * A198245 A198246 A198247 KEYWORD nonn AUTHOR Jonathan Vos Post, Dec 21 2012 EXTENSIONS a(5)-a(6) from Robert G. Wilson v, Dec 21 2012 a(7) from Michael B. Porter, Dec 27 2012 Corrected terms a(6)-a(7) and added terms by Chai Wah Wu, Nov 09 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 6 10:23 EST 2022. Contains 358630 sequences. (Running on oeis4.)