cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A286301 Primes of the form p^10 + p^9 + p^8 + p^7 + p^6 + p^5 + p^4 + p^3 + p^2 + p + 1 when p is prime.

Original entry on oeis.org

12207031, 2141993519227, 178250690949465223, 2346320474383711003267, 398341412240537151131351, 79545183674814239059370551, 494424256962371823779424877, 8271964541879648991904246901, 32142180034067960734115528951, 91264002187709396686868598317
Offset: 1

Views

Author

Hartmut F. W. Hoft, May 05 2017

Keywords

Examples

			Prime number 12207031 = Sum_{i=0..10} 5^i is the first in the sequence since 23 divides 88573 = Sum_{i=0..10} 3^i as well as 2047 = Sum_{i=0..10} 2^i.
		

Crossrefs

Subsequence of A060885, A162861 and A193574.

Programs

  • Mathematica
    a286301[n_] := Select[Map[(Prime[#]^11-1)/(Prime[#]-1)&, Range[n]], PrimeQ]
    a286301[150] (* data *)

A253240 Square array read by antidiagonals: T(m, n) = Phi_m(n), the m-th cyclotomic polynomial at x=n.

Original entry on oeis.org

1, 1, -1, 1, 0, 1, 1, 1, 2, 1, 1, 2, 3, 3, 1, 1, 3, 4, 7, 2, 1, 1, 4, 5, 13, 5, 5, 1, 1, 5, 6, 21, 10, 31, 1, 1, 1, 6, 7, 31, 17, 121, 3, 7, 1, 1, 7, 8, 43, 26, 341, 7, 127, 2, 1, 1, 8, 9, 57, 37, 781, 13, 1093, 17, 3, 1, 1, 9, 10, 73, 50, 1555, 21, 5461, 82, 73, 1, 1, 1, 10, 11, 91, 65, 2801, 31, 19531, 257, 757, 11, 11, 1, 1, 11, 12, 111, 82, 4681, 43, 55987, 626, 4161, 61, 2047, 1, 1
Offset: 0

Views

Author

Eric Chen, Apr 22 2015

Keywords

Comments

Outside of rows 0, 1, 2 and columns 0, 1, only terms of A206942 occur.
Conjecture: There are infinitely many primes in every row (except row 0) and every column (except column 0), the indices of the first prime in n-th row and n-th column are listed in A117544 and A117545. (See A206864 for all the primes apart from row 0, 1, 2 and column 0, 1.)
Another conjecture: Except row 0, 1, 2 and column 0, 1, the only perfect powers in this table are 121 (=Phi_5(3)) and 343 (=Phi_3(18)=Phi_6(19)).

Examples

			Read by antidiagonals:
m\n  0   1   2   3   4   5   6   7   8   9  10  11  12
------------------------------------------------------
0    1   1   1   1   1   1   1   1   1   1   1   1   1
1   -1   0   1   2   3   4   5   6   7   8   9  10  11
2    1   2   3   4   5   6   7   8   9  10  11  12  13
3    1   3   7  13  21  31  43  57  73  91 111 133 157
4    1   2   5  10  17  26  37  50  65  82 101 122 145
5    1   5  31 121 341 781 ... ... ... ... ... ... ...
6    1   1   3   7  13  21  31  43  57  73  91 111 133
etc.
The cyclotomic polynomials are:
n        n-th cyclotomic polynomial
0        1
1        x-1
2        x+1
3        x^2+x+1
4        x^2+1
5        x^4+x^3+x^2+x+1
6        x^2-x+1
...
		

Crossrefs

Main diagonal is A070518.
Indices of primes in n-th column for n = 1-10 are A246655, A072226, A138933, A138934, A138935, A138936, A138937, A138938, A138939, A138940.
Indices of primes in main diagonal is A070519.
Cf. A117544 (indices of first prime in n-th row), A085398 (indices of first prime in n-th row apart from column 1), A117545 (indices of first prime in n-th column).
Cf. A206942 (all terms (sorted) for rows>2 and columns>1).
Cf. A206864 (all primes (sorted) for rows>2 and columns>1).

Programs

  • Mathematica
    Table[Cyclotomic[m, k-m], {k, 0, 49}, {m, 0, k}]
  • PARI
    t1(n)=n-binomial(floor(1/2+sqrt(2+2*n)), 2)
    t2(n)=binomial(floor(3/2+sqrt(2+2*n)), 2)-(n+1)
    T(m, n) = if(m==0, 1, polcyclo(m, n))
    a(n) = T(t1(n), t2(n))

Formula

T(m, n) = Phi_m(n)

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.

Original entry on oeis.org

11, 10778947368421, 17513875027111, 610851724137931, 614910264406779661, 22390512687494871811, 22793803793211153712637, 79905927161140977116221, 184251916941751188170917, 319465039747605973452001, 1311848376806967295019263, 1918542715220370688851293
Offset: 1

Views

Author

Jonathan Vos Post, Dec 21 2012

Keywords

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)

Examples

			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.
		

Crossrefs

Similar to A185632 (k^2+ ...), A193366 (k^4+ ...), A194194 (k^6+ ...).

Programs

  • 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
    
  • 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
  • PARI
    forcomposite(n=0,10^3,my(t=sum(k=0,10,n^k));if(isprime(t),print1(t,", "))); \\ Joerg Arndt, Nov 10 2014
  • 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
    

Formula

{A060885(A018252(n)) which are in A000040}.

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

A020519 11th cyclotomic polynomial evaluated at powers of 2.

Original entry on oeis.org

11, 2047, 1398101, 1227133513, 1172812402961, 1162219258676257, 1171221845949812801, 1189887617730934227073, 1213666705181745367548161, 1240362622532514091484054017, 1268889750375080065623288448001, 1298708349570020393652962442872833
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Maple
    with(numtheory,cyclotomic):seq(cyclotomic(11,2^i),i=0..24);
  • Mathematica
    Table[Total[x^Range[0,10]],{x,2^Range[0,10]}] (* Harvey P. Dale, Mar 05 2014 *)
  • PARI
    a(n) = polcyclo(11, 2^n); \\ Michel Marcus, Apr 12 2014

Formula

G.f.: -(72022409665839104*x^10 -95936100375199744*x^9 +41035167933923328*x^8 -7266644321632256*x^7 +581441424424960*x^6 -21804053415936*x^5 +388080675136*x^4 -3261182144*x^3 +12564486*x^2 -20470*x +11) / ((x -1)*(2*x -1)*(4*x -1)*(8*x -1)*(16*x -1)*(32*x -1)*(64*x -1)*(128*x -1)*(256*x -1)*(512*x -1)*(1024*x -1)). - Colin Barker, Feb 14 2015
a(n) = 1+2^n+4^n+8^n+16^n+32^n+64^n+128^n+256^n+512^n+1024^n. - Colin Barker, Feb 15 2015
a(n) = A060885(A000079(n)). - Michel Marcus, Apr 06 2016

A326618 a(n) = n^18 + n^9 + 1.

Original entry on oeis.org

1, 3, 262657, 387440173, 68719738881, 3814699218751, 101559966746113, 1628413638264057, 18014398643699713, 150094635684419611, 1000000001000000001, 5559917315850179173, 26623333286045024257, 112455406962561892503, 426878854231297789441, 1477891880073843750001
Offset: 0

Views

Author

Richard N. Smith, Jul 15 2019

Keywords

Comments

a(n) = Phi_27(n) where Phi_k(x) is the k-th cyclotomic polynomial.

Crossrefs

Sequences of the type Phi_k(n), where Phi_k is the k-th cyclotomic polynomial: A000012 (k=0), A023443 (k=1), A000027 (k=2), A002061 (k=3), A002522 (k=4), A053699 (k=5), A002061 (k=6), A053716 (k=7), A002523 (k=8), A060883 (k=9), A060884 (k=10), A060885 (k=11), A060886 (k=12), A060887 (k=13), A060888 (k=14), A060889 (k=15), A060890 (k=16), A269442 (k=17), A060891 (k=18), A269446 (k=19), A060892 (k=20), A269483 (k=21), A269486 (k=22), A060893 (k=24), A269527 (k=25), A266229 (k=26), this sequence (k=27), A270204 (k=28), A060894 (k=30), A060895 (k=32), A060896 (k=36).
Cf. A153440 (indices of prime terms).

Programs

  • Magma
    [n^18+n^9+1: n in [0..17]]; // Vincenzo Librandi, Jul 15 2019
    
  • Mathematica
    Table[n^18 + n^9 + 1, {n, 0, 17}] (* Vincenzo Librandi, Jul 15 2019 *)
    Table[Cyclotomic[27, n], {n, 0, 17}]
  • PARI
    a(n) = polcyclo(27, n); \\ Michel Marcus, Jul 20 2019
Previous Showing 11-15 of 15 results.