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.

Showing 1-10 of 17 results. Next

A270799 Artiads (A001583) congruent to 1 mod 50 and having 2 as a quintic residue.

Original entry on oeis.org

3251, 4751, 14251, 17401, 21401, 27551, 32051, 32251, 36151, 36451, 42451, 51001, 52501, 54101, 55001, 56501, 59051, 60101, 61051, 83401, 104801, 113051, 116101, 119851, 121351, 170701, 174901, 178501, 178601, 179051, 182101, 185951, 190301, 202751, 213901
Offset: 1

Views

Author

N. J. A. Sloane, Apr 01 2016

Keywords

Crossrefs

Cf. A001583.

Programs

  • Sage
    def isa(n) : return n % 50 == 1 and is_prime(n) and 2.powermod((n-1)//5, n) == 1 and fibonacci((n - 1)//5) % n == 0 # Eric M. Schmidt, Apr 01 2016

Extensions

Definition edited by and more terms from Eric M. Schmidt, Apr 01 2016

A271210 Artiads (A001583) congruent to 1 mod 50 and for which 5 is a quintic residue.

Original entry on oeis.org

13451, 15901, 19001, 19801, 21701, 22901, 28001, 38851, 50551, 64301, 65101, 66851, 78101, 89101, 94351, 95701, 96401, 117751, 124001, 126001, 127951, 136601, 138401, 150301, 162251, 164701, 167051, 178301, 178501, 181001, 183301, 185051, 185401, 185951, 186301
Offset: 1

Views

Author

Eric M. Schmidt, Apr 02 2016

Keywords

Comments

Hyperartiads (A270798) congruent to 1 mod 50.

Crossrefs

Programs

  • Sage
    def isa(n) : return n % 50 == 1 and is_prime(n) and 5.powermod((n-1)//5, n) == 1 and fibonacci((n - 1)//5) % n == 0

A030430 Primes of the form 10*n+1.

Original entry on oeis.org

11, 31, 41, 61, 71, 101, 131, 151, 181, 191, 211, 241, 251, 271, 281, 311, 331, 401, 421, 431, 461, 491, 521, 541, 571, 601, 631, 641, 661, 691, 701, 751, 761, 811, 821, 881, 911, 941, 971, 991, 1021, 1031, 1051, 1061, 1091, 1151, 1171, 1181, 1201, 1231, 1291
Offset: 1

Views

Author

Keywords

Comments

Also primes of form 5*n+1 or equivalently 5*n+6.
Primes p such that the arithmetic mean of divisors of p^4 is an integer: A000203(p^4)/A000005(p^4) = C. - Ctibor O. Zizka, Sep 15 2008
Being a subset of A141158, this is also a subset of the primes of form x^2-5*y^2. - Tito Piezas III, Dec 28 2008
5 is quadratic residue of primes of this form. - Vincenzo Librandi, Jun 25 2014
Primes p such that 5 divides sigma(p^4), cf. A274397. - M. F. Hasler, Jul 10 2016

Crossrefs

Cf. A024912, A045453, A049511, A081759, A017281, A010051, A004615 (multiplicative closure).
Cf. A001583 (subsequence).
Union of A132230 and A132232. - Ray Chandler, Apr 07 2009

Programs

  • Haskell
    a030430 n = a030430_list !! (n-1)
    a030430_list = filter ((== 1) . a010051) a017281_list
    -- Reinhard Zumkeller, Apr 16 2012
    
  • Mathematica
    Select[Prime@Range[210], Mod[ #, 10] == 1 &] (* Ray Chandler, Dec 06 2006 *)
    Select[Range[11,1291,10],PrimeQ] (*Zak Seidov, Aug 14 2011*)
  • PARI
    is(n)=n%10==1 && isprime(n) \\ Charles R Greathouse IV, Sep 06 2012
    
  • PARI
    lista(nn) = forprime(p=11, nn, if(p%10==1, print1(p, ", "))) \\ Iain Fox, Dec 30 2017

Formula

a(n) = 10*A024912(n)+1 = 5*A081759(n)+6.
A104146(floor(a(n)/10)) = 1.
Union of A132230 and A132232. - Ray Chandler, Apr 07 2009
a(n) ~ 4n log n. - Charles R Greathouse IV, Sep 06 2012
Intersection of A000040 and A017281. - Iain Fox, Dec 30 2017

A047650 Primes for which golden mean tau is a quadratic residue.

Original entry on oeis.org

29, 89, 101, 181, 229, 349, 401, 461, 509, 521, 541, 709, 761, 769, 809, 941, 1009, 1021, 1049, 1061, 1109, 1229, 1249, 1289, 1361, 1409, 1549, 1601, 1621, 1669, 1709, 1721, 1741, 1789, 1861, 2029, 2069, 2081, 2089, 2389, 2441, 2621, 2729, 2801, 2861
Offset: 0

Views

Author

Keywords

Comments

Primes of the form x^2 + 20*y^2. - T. D. Noe, May 08 2005
Also primes p that divide the sum of cubes of the first (p-1)/2 Fibonacci numbers A005968((p-1)/2). - Alexander Adamchuk, Aug 07 2006
From A.H.M. Smeets, Nov 16 2023: (Start)
Mean gap size between two consecutive terms at p: ~ 8*log(p).
In x^2 + 20y^2: x == 1 (mod 2) and x !== 5 (mod 10). Otherwise not prime. (End)

Crossrefs

Programs

  • Magma
    k:=20; [p: p in PrimesUpTo(3000) | NormEquation(k, p) eq true]; // Vincenzo Librandi, Sep 05 2016
  • Mathematica
    nn=20; pMax=3000; Union[Reap[Do[p=x^2 + nn*y^2; If[p<=pMax&&PrimeQ[p], Sow[p]], {x, Sqrt[pMax]}, {y, Sqrt[pMax/nn]}]][[2, 1]]] (* Vincenzo Librandi, Sep 05 2016 *)

Formula

From A.H.M. Smeets, Nov 16 2023: (Start)
Equals {prime(n): A296240(n) in {2^k: k > 0}} = {A308787} union {A308789} union {A308793} union ... .
a(n) ~ A000040(8*n). (End)

Extensions

More terms from James Sellers, Jan 25 2000

A270800 Septic artiads: primes p congruent to 1 mod 14 for which all solutions of the congruence x^3 + x^2 - 2x - 1 == 0 (mod p) are 7th power residues.

Original entry on oeis.org

14197, 21617, 23801, 24977, 25999, 34763, 37549, 41959, 42407, 45053, 45599, 54713, 55987, 56099, 60271, 61657, 63463, 66067, 72577, 75307, 76343, 76777, 79283, 83357, 88397, 90469, 91309, 99611, 107927, 111217, 111301, 111791, 124699, 126127, 131251, 132287
Offset: 1

Views

Author

N. J. A. Sloane, Apr 01 2016

Keywords

Crossrefs

Cf. A001583.

Programs

  • Sage
    def is_septic_artiad(n) :
        if not (n % 14 == 1 and is_prime(n)) : return False
        R. = PolynomialRing(GF(n))
        return all(r[0]^((n-1)//7) == 1 for r in (t^3 + t^2 - 2*t - 1).roots())
    # Eric M. Schmidt, Apr 02 2016

Extensions

Definition added and sequence extended and corrected by Eric M. Schmidt, Apr 02 2016

A047652 Primes for which golden mean is a cubic residue.

Original entry on oeis.org

139, 151, 199, 331, 541, 619, 661, 709, 811, 829, 919, 1069, 1231, 1279, 1291, 1381, 1471, 1579, 1699, 1999, 2161, 2221, 2239, 2251, 2281, 2371, 2389, 2521, 2659, 2689, 2749, 3001, 3121, 3271, 3331, 3391, 3499, 3529, 3571, 3631, 3919, 4021, 4051, 4159
Offset: 1

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Author

Keywords

Comments

Primes of the form x^2 + xy + 34y^2, whose discriminant is -135. - T. D. Noe, May 17 2005
Primes of the form x^2 + 135*y^2. - Arkadiusz Wesolowski, May 31 2015

Crossrefs

Cf. A047650.

Programs

  • Mathematica
    Select[Prime[Range[1000]],IntegerQ[Fibonacci[(#1-1)/3]/#1]&] (* Alexander Adamchuk, Sep 16 2006 *)

Formula

Primes p that divide Fibonacci((p-1)/3). - Alexander Adamchuk, Sep 16 2006

Extensions

More terms from James Sellers, Jan 25 2000

A125253 Primes p that divide Fibonacci[(p-1)/7].

Original entry on oeis.org

2269, 2521, 2731, 2969, 3571, 3739, 4481, 4831, 5741, 6091, 6329, 6581, 9521, 10949, 11159, 11789, 12391, 13049, 13679, 14281, 14449, 14771, 16829, 16871, 18229, 19489, 19559, 20021, 20399, 21701, 23269, 24179, 24571, 26111, 29191, 31039
Offset: 1

Views

Author

Alexander Adamchuk, Nov 26 2006

Keywords

Crossrefs

Cf. A125252 = Primes p that divide Fibonacci[(p+1)/7]. Cf. A122487 = Primes p that divide Fibonacci[(p+1)/2]. Cf. A047652 = Primes p that divide Fibonacci[(p-1)/3]. Cf. A001583 = Artiads. Primes p that divide Fibonacci[(p-1)/5].

Programs

  • Mathematica
    Select[Prime[Range[5000]], IntegerQ[Fibonacci[(#1-1)/7]/#1]&]

A270798 Hyperartiads.

Original entry on oeis.org

5281, 5591, 6211, 6271, 8581, 8861, 9011, 9661, 10391, 10691, 11621, 12011, 12911, 13451, 15901, 19001, 19801, 20521, 20921, 21481, 21701, 22901, 22921, 23371, 26141, 27241, 27481, 28001, 28711, 29131, 30971, 31321, 31511, 32341, 32381, 34211, 38261, 38611
Offset: 1

Views

Author

N. J. A. Sloane, Mar 31 2016

Keywords

Comments

Artiads (A001583) for which 5 is a quintic residue. [Lehmer] - Eric M. Schmidt, Apr 01 2016

Crossrefs

Cf. A001583.

Programs

  • Sage
    def is_hyperartiad(n) : return n % 10 == 1 and is_prime(n) and 5.powermod((n-1)//5, n) == 1 and fibonacci((n-1)//5) % n == 0 # Eric M. Schmidt, Apr 01 2016

Extensions

Extended and corrected by Eric M. Schmidt, Apr 01 2016

A168171 Least prime p = 1 (mod n) which divides Fibonacci((p-1)/n).

Original entry on oeis.org

11, 29, 139, 61, 211, 541, 2269, 89, 199, 281, 859, 661, 911, 2269, 2221, 2081, 2789, 2161, 3041, 421, 2521, 19009, 21529, 3001, 9901, 5981, 2161, 2269, 26449, 2221, 31249, 19681, 17491, 2789, 3571, 25309, 30859, 3041, 6709, 3001, 9349, 2521, 13159, 19009
Offset: 1

Views

Author

M. F. Hasler, Nov 25 2009

Keywords

Examples

			For n=1, all numbers p satisfy p=1 (mod n), but p=11 is the least prime that divides F((p-1)/1)=F(p-1)=F(10)=55.
For n=2, all odd numbers, thus all primes p>2, satisfy p=1 (mod n), but p=29 is the first one to divide F((p-1)/2) = F(14) = 377 = 13*29.
For n=5, a(n)=211 is the smallest Artiad, i.e. prime p=1 (mod 5) which divides F((p-1)/5) = F(42) = 211*1269736.
		

Crossrefs

Cf. A122487 (p | F[(p+1)/2]), A047652 (p | F[(p-1)/3]), A001583 (Artiads: p | F[(p-1)/5]), A125252 (p | F[(p+1)/7]), A125253 (p | F[(p-1)/7]).

Programs

  • Mathematica
    a[1] = 11;
    a[n_] := For[p = 1, True, p = p + n, If[PrimeQ[p] && Divisible[Fibonacci[(p - 1)/n], p], Return[p]]];
    a /@ Range[100] (* Jean-François Alcover, Oct 14 2019 *)
  • PARI
    for(n=1,99,forprime(p=1,oo,(p-1)%n & next; fibonacci((p-1)/n)%p || print1(p, ", ") || next(2)))

A270801 Septic hyperartiads: septic artiads (A270800) for which 7 is a 7th power residue.

Original entry on oeis.org

665897, 741413, 794207, 859601, 876611, 892627, 980911, 1102249, 1116977, 1123879, 1129213, 1163653, 1228543, 1237139, 1393771, 1434553, 1453019, 1471079, 1513163, 1570577, 1588133, 1608769, 1638211, 1638743, 1645253, 1670887, 1702933, 1704137, 1785337
Offset: 1

Views

Author

N. J. A. Sloane, Apr 01 2016, typo corrected Apr 02 2016

Keywords

Crossrefs

Programs

  • Sage
    def is_septic_hyperartiad(n) :
        if not (n % 14 == 1 and is_prime(n)) : return false
        R. = PolynomialRing(GF(n))
        return 7.powermod((n-1)//7, n) == 1 and all(r[0]^((n-1)//7) == 1 for r in (t^3 + t^2 - 2*t - 1).roots())
    # Eric M. Schmidt, Apr 02 2016

Extensions

Definition corrected by and more terms from Eric M. Schmidt, Apr 02 2016
Showing 1-10 of 17 results. Next