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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A273222 a(n) = p*(p - 1)*(73*p^2 - 45*p + 14)/24, where p = prime(n).

Original entry on oeis.org

18, 134, 1345, 5733, 38280, 76479, 230588, 363546, 792649, 2033451, 2664915, 5454873, 8260270, 10012464, 14337303, 23275109, 35855716, 41007555, 59825238, 75546485, 84478374, 116064351, 141557994, 187394306, 264812328, 311476425, 336995709, 392705408, 423017991
Offset: 1

Views

Author

Vincenzo Librandi, May 19 2016

Keywords

Crossrefs

Programs

  • Magma
    [p*(p-1)*(73*p^2-45*p+14)/24: p in PrimesUpTo(200)];
  • Mathematica
    Table[p = Prime[n]; p (p - 1) (73 p^2 - 45 p + 14) / 24, {n, 40}]
    (#(#-1)(73#^2-45#+14))/24&/@Prime[Range[30]] (* Harvey P. Dale, Jan 17 2017 *)

A121057 Triangle read by rows: T(n,m) = Prime[m]^n*(Prime[m] - 1)/2.

Original entry on oeis.org

1, 3, 9, 10, 50, 250, 21, 147, 1029, 7203, 55, 605, 6655, 73205, 805255, 78, 1014, 13182, 171366, 2227758, 28960854, 136, 2312, 39304, 668168, 11358856, 193100552, 3282709384, 171, 3249, 61731, 1172889, 22284891, 423412929, 8044845651
Offset: 1

Views

Author

Roger L. Bagula, May 27 2007

Keywords

Comments

Row sums are 1, 12, 310, 8400, 885775, 31374252, 3487878712, 161343848880, 20713255606813, 6100254882852900, ...
First column is A008837. - Michel Marcus, Apr 11 2013

Examples

			Triangle begins
1;
3, 9;
10, 50, 250;
21, 147, 1029, 7203;
		

Programs

  • Mathematica
    t[n_, m_] = Prime[m]^n*(Prime[m] - 1)/2; a = Table[Table[t[n, m], {n, 1, m}], {m, 1, 10}] Flatten[a]
  • PARI
    trga(nrows) = {for (n=1, nrows, for (m=1, n, print1(prime(n)^m*(prime(n) - 1)/2, ", ");); print(););}  \\ Michel Marcus, Apr 11 2013

A138459 a(n) = ((n-th prime)^6-(n-th prime)^4)/12.

Original entry on oeis.org

4, 54, 1250, 9604, 146410, 399854, 2004504, 3909630, 12313004, 49509670, 73881680, 213654354, 395606540, 526495354, 897861304, 1846372554, 3514034690, 4292210710, 7536519254, 10672906020, 12608819004, 20254042120, 27241076254
Offset: 1

Views

Author

Artur Jasinski, Mar 22 2008

Keywords

Comments

Differences (p^k-p^m)/q such that k > m:
p^2-p is given in A036689
(p^2-p)/2 is given in A008837
p^3-p is given in A127917
(p^3-p)/2 is given in A127918
(p^3-p)/3 is given in A127919
(p^3-p)/6 is given in A127920
p^3-p^2 is given in A135177
(p^3-p^2)/2 is given in A138416
p^4-p is given in A138401
(p^4-p)/2 is given in A138417
p^4-p^2 is given in A138402
(p^4-p^2)/2 is given in A138418
(p^4-p^2)/3 is given in A138419
(p^4-p^2)/4 is given in A138420
(p^4-p^2)/6 is given in A138421
(p^4-p^2)/12 is given in A138422
p^4-p^3 is given in A138403
(p^4-p^3)/2 is given in A138423
p^5-p is given in A138404
(p^5-p)/2 is given in A138424
(p^5-p)/3 is given in A138425
(p^5-p)/5 is given in A138426
(p^5-p)/6 is given in A138427
(p^5-p)/10 is given in A138428
(p^5-p)/15 is given in A138429
(p^5-p)/30 is given in A138430
p^5-p^2 is given in A138405
(p^5-p^2)/2 is given in A138431
p^5-p^3 is given in A138406
(p^5-p^3)/2 is given in A138432
(p^5-p^3)/3 is given in A138433
(p^5-p^3)/4 is given in A138434
(p^5-p^3)/6 is given in A138435
(p^5-p^3)/8 is given in A138436
(p^5-p^3)/12 is given in A138437
(p^5-p^3)/24 is given in A138438
p^5-p^4 is given in A138407
(p^5-p^4)/2 is given in A138439
p^6-p is given in A138408
(p^6-p)/2 is given in A138440
p^6-p^2 is given in A138409
(p^6-p^2)/2 is given in A138441
(p^6-p^2)/3 is given in A138442
(p^6-p^2)/4 is given in A138443
(p^6-p^2)/5 is given in A138444
(p^6-p^2)/6 is given in A138445
(p^6-p^2)/10 is given in A138446
(p^6-p^2)/12 is given in A138447
(p^6-p^2)/15 is given in A138448
(p^6-p^2)/20 is given in A122220
(p^6-p^2)/30 is given in A138450
(p^6-p^2)/60 is given in A138451
p^6-p^3 is given in A138410
(p^6-p^3)/2 is given in A138452
p^6-p^4 is given in A138411
(p^6-p^4)/2 is given in A138453
(p^6-p^4)/3 is given in A138454
(p^6-p^4)/4 is given in A138455
(p^6-p^4)/6 is given in A138456
(p^6-p^4)/8 is given in A138457
(p^6-p^4)/12 is given in A138458
(p^6-p^4)/24 is given in A138459
p^6-p^5 is given in A138412
(p^6-p^5)/2 is given in A138460

Programs

  • Mathematica
    a = {}; Do[p = Prime[n]; AppendTo[a, (p^6 - p^4)/12], {n, 1, 24}]; a
  • PARI
    forprime(p=2,1e3,print1((p^6-p^4)/12", ")) \\ Charles R Greathouse IV, Jul 15 2011

A231808 Numerator of asymptotic density of Union{H_p: p is odd prime and p <= n-th prime}, where H_p is {K*p*(p-1)/2 : K integer}.

Original entry on oeis.org

0, 1, 2, 2, 67, 67, 230, 230, 5317, 70307, 70307, 70307, 70307, 70307, 23158993, 58560723101, 10373287618037, 10373287618037, 10373287618037, 736719736564627, 736719736564627, 736719736564627, 119433196256360189, 1970856524120023, 1970856524120023, 1970856524120023
Offset: 1

Views

Author

Keywords

Comments

a(n)/A231809(n) is the asymptotic density of Union{H_p: p is odd prime and p <= n-th prime}, where H_p is {K*p*(p-1)/2 : K integer}; a(n) tends to 0.41.. (the asymptotic density of A229307 = Union{H_p: p odd prime}).

Examples

			0, 1/3, 2/5, 2/5, 67/165, 67/165, 230/561, 230/561, 5317/12903, 70307/170085, 70307/170085, 70307/170085, 70307/170085, 70307/170085, 23158993/55957965, 58560723101/141368472245, 10373287618037/25022219587365, ....
		

Crossrefs

Programs

  • Mathematica
    << DiscreteMath`Combinatorica` (*ver 5.0*)
    << Combinatorica` (*ver 8.0*)
    fa[n_] := FactorInteger[n]; lcm[lis_] := lcm[lis] = {aux = 1; Do[aux = LCM[aux, lis[[i]]], {i, 1, Length@lis}]; aux}[[1]]; inclusexclus[lis_] := inclusexclus[lis] =Sum[(-1)^(1 + Length[lis[[i]]])/lcm[lis[[i]]], {i, 1, Length@lis}]; densidad[lis_] := Sum[inclusexclus[KSubsets[lis, i]], {i, 1, Length[lis]}]; lista[n_] := Table[(Prime[i]^2 - Prime[i])/2, {i, 2, n}]; Table[Numerator@densidad[lista[i]], {i, 1, 15}]

A231809 Denominator of asymptotic density of Union{H_p: p is odd prime and p <= n-th prime}, where H_p is {K*p*(p-1)/2 : K integer}.

Original entry on oeis.org

1, 3, 5, 5, 165, 165, 561, 561, 12903, 170085, 170085, 170085, 170085, 170085, 55957965, 141368472245, 25022219587365, 25022219587365, 25022219587365, 1776577590702915, 1776577590702915, 1776577590702915, 287890168626762845, 4749253940274679, 4749253940274679
Offset: 1

Views

Author

Keywords

Comments

See A231808.

Examples

			0, 1/3, 2/5, 2/5, 67/165, 67/165, 230/561, 230/561, 5317/12903, 70307/170085, 70307/170085, 70307/170085, 70307/170085, 70307/170085, 23158993/55957965, 58560723101/141368472245, 10373287618037/25022219587365
		

Crossrefs

Programs

  • Mathematica
    << DiscreteMath`Combinatorica` (*ver 5.0*)
    << Combinatorica` (*ver 8.0*)
    fa[n_] := FactorInteger[n]; lcm[lis_] := lcm[lis] = {aux = 1; Do[aux = LCM[aux, lis[[i]]], {i, 1, Length@lis}]; aux}[[1]]; inclusexclus[lis_] := inclusexclus[lis] =Sum[(-1)^(1 + Length[lis[[i]]])/lcm[lis[[i]]], {i, 1, Length@lis}]; densidad[lis_] := Sum[inclusexclus[KSubsets[lis, i]], {i, 1, Length[lis]}]; lista[n_] := Table[(Prime[i]^2 - Prime[i])/2, {i, 2, n}]; Table[Denominator@densidad[lista[i]], {i, 1, 15}]

A273223 a(n) = p*(p - 1)*(501*p^3 - 414*p^2 + 111*p - 54)/120, where p = prime(n).

Original entry on oeis.org

42, 504, 8796, 53298, 566412, 1341756, 5312160, 9373536, 24790458, 80346588, 112613886, 275440284, 462452448, 588037212, 920759046, 1686448764, 2893307844, 3421602972, 5484429720, 7340452434, 8440231968, 12551864598, 16086117120, 22838112000, 35181089856
Offset: 1

Views

Author

Vincenzo Librandi, May 19 2016

Keywords

Crossrefs

Programs

  • Magma
    [p*(p-1)*(501*p^3-414*p^2+111*p-54)/120: p in PrimesUpTo(200)];
  • Mathematica
    Table[p = Prime[n]; p (p - 1) (501 p^3 - 414 p^2 + 111 p - 54) / 120, {n, 40}]

A061591 a(n) = 2^x, where x = p*(p-1)/2 and p is the n-th prime.

Original entry on oeis.org

2, 8, 1024, 2097152, 36028797018963968, 302231454903657293676544, 87112285931760246646623899502532662132736, 2993155353253689176481146537402947624255349848014848
Offset: 1

Views

Author

Labos Elemer, May 22 2001

Keywords

Crossrefs

Cf. A007955, A006308. The exponents x are in A008837.

Programs

  • Mathematica
    Table[2^((p(p-1))/2),{p,Prime[Range[10]]}] (* Harvey P. Dale, Sep 03 2024 *)
  • PARI
    { n=0; forprime (p=2, prime(22), write("b061591.txt", n++, " ", 2^(p*(p - 1)/2)) ) } \\ Harry J. Smith, Jul 25 2009

Extensions

Offset changed from 2 to 1 by Harry J. Smith, Jul 25 2009

A164623 Primes p such that p*(p-1)/2-5 and p*(p-1)/2+5 are also prime numbers.

Original entry on oeis.org

13, 157, 673, 1069, 1117, 1153, 1213, 1597, 2029, 2089, 2437, 2713, 2833, 3613, 4057, 4909, 5653, 6337, 6529, 7549, 7993, 8053, 9613, 10789, 11497, 11689, 12073, 12373, 13309, 13669, 13789, 14173, 15289, 15937, 16249, 18097, 18637, 19249, 19993
Offset: 1

Views

Author

Keywords

Comments

Primes A000040(k) such that A008837(k)+-5 are also prime numbers.

Examples

			13 is in the sequence because 13*6-5=73 and 13*6+5=83 are both prime.
		

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[2300]], PrimeQ[# (# - 1)/2 - 5] && PrimeQ[# (# - 1)/2 + 5] &]
  • PARI
    forprime(p=2,10^6,my(b=binomial(p,2));if(isprime(b-5)&isprime(b+5),print1(p,", "))); /* Joerg Arndt, Apr 10 2013 */

Extensions

Edited by R. J. Mathar, Aug 20 2009
Mathematica code adapted to the definition by Bruno Berselli, Apr 10 2013

A253655 Number of monic irreducible polynomials of degree 6 over GF(prime(n)).

Original entry on oeis.org

9, 116, 2580, 19544, 295020, 804076, 4022064, 7839780, 24670536, 99133020, 147912160, 427612404, 791672280, 1053546956, 1796518224, 3694034916, 7030054140, 8586690620, 15076346164, 21349986840, 25222305336, 40514492720, 54489965796, 82830096360, 138828513824, 176919851700
Offset: 1

Views

Author

Robert Israel, Jan 07 2015

Keywords

Examples

			For n=1 the a(1) = 9 irreducible monic polynomials of degree 6 over GF(2) are
x^6+x^5+1, x^6+x^3+1, x^6+x^5+x^4+x^2+1, x^6+x^5+x^3+x^2+1, x^6+x+1, x^6+x^5+x^4+x+1, x^6+x^4+x^3+x+1, x^6+x^5+x^2+x+1, x^6+x^4+x^2+x+1.
		

Crossrefs

Programs

  • Magma
    [(p^6 - p^3 - p^2 + p) div 6: p in PrimesUpTo(110)]; // Vincenzo Librandi, Jan 08 2015
  • Maple
    f:= p-> (p^6 - p^3 - p^2 + p)/6:
    seq(f(ithprime(i)), i=1..100); # Robert Israel, Jan 07 2015
  • Mathematica
    Table[(Prime[n]^6 - Prime[n]^3 - Prime[n]^2 + Prime[n]) / 6, {n, 1, 30}] (* Vincenzo Librandi, Jan 08 2015 *)

Formula

a(n) = (p^6 - p^3 - p^2 + p)/6, where p = prime(n).

A261365 Prime-numbered rows of Pascal's triangle.

Original entry on oeis.org

1, 2, 1, 1, 3, 3, 1, 1, 5, 10, 10, 5, 1, 1, 7, 21, 35, 35, 21, 7, 1, 1, 11, 55, 165, 330, 462, 462, 330, 165, 55, 11, 1, 1, 13, 78, 286, 715, 1287, 1716, 1716, 1287, 715, 286, 78, 13, 1, 1, 17, 136, 680, 2380, 6188, 12376, 19448, 24310, 24310, 19448, 12376, 6188, 2380, 680, 136, 17, 1, 1, 19, 171, 969, 3876, 11628, 27132, 50388, 75582, 92378, 92378, 75582, 50388, 27132, 11628, 3876, 969, 171, 19, 1
Offset: 1

Views

Author

Maghraoui Abdelkader, Aug 16 2015

Keywords

Examples

			1,2,1;
1,3,3,1;
1,5,10,10,5,1;
1,7,21,35,35,21,7,1;
1,11,55,165,330,462,462,330,165,55,11,1;
		

Crossrefs

Cf. A000040 (2nd column), A008837 (3rd column).

Programs

  • Mathematica
    Table[Binomial[Prime@ n, k], {n, 8}, {k, 0, Prime@ n}] // Flatten (* Michael De Vlieger, Aug 20 2015 *)
  • PARI
    forprime(n=2, 20, for(k=0,n,print1(binomial(n,k),", ")))

Formula

T(n,k) = binomial(prime(n), k).
Previous Showing 21-30 of 31 results. Next