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 10 results.

A183010 a(n) = 24*n - 1.

Original entry on oeis.org

-1, 23, 47, 71, 95, 119, 143, 167, 191, 215, 239, 263, 287, 311, 335, 359, 383, 407, 431, 455, 479, 503, 527, 551, 575, 599, 623, 647, 671, 695, 719, 743, 767, 791, 815, 839, 863, 887, 911, 935, 959, 983, 1007, 1031, 1055, 1079, 1103, 1127, 1151, 1175, 1199
Offset: 0

Views

Author

Omar E. Pol, Jan 21 2011

Keywords

Comments

a(n) is also the denominator of the finite algebraic formula for the number of partitions of n, if n >= 1. The formula is p(n) = Tr(n)/(24*n - 1), n >= 1. See theorem 1.1 of the Bruinier-Ono paper in the link. For the numerators see A183011.
It appears that a(n) is also the denominator of the coefficient of the third term in the n-th Bruinier-Ono "partition polynomial" H_n(x). See the Bruinier-Ono paper, chapter 5 "Examples". For the numerators see A183007. - Omar E. Pol, Jul 13 2011
Also exponents in the formula q^(-1) + q^23 + 2*q^47 + 3*q^71 + 5*q^95 + 7*q^119 + 11*q^143 + 15*q^167 + ... in which the coefficients are the partition numbers (see A000041, Example section). - Omar E. Pol, Feb 27 2013

Examples

			G.f. = -1 + 23*x + 47*x^2 + 71*x^3 + 95*x^4 + 119*x^5 + 143*x^6 + 167*x^7 + ...
		

Crossrefs

Cf. A000041, A000203, A008606, A134517 (subset of primes), A183009, A183011, A187206, A280097 (sum of divisors), A280098.
Cf. A008594.

Programs

Formula

a(n) = A008606(n) - 1.
a(1)=23, a(2)=47, a(n) = 2*a(n-1) - a(n-2). - Vincenzo Librandi, Jan 23 2011
a(n) = A183011(n)/A000041(n). - Omar E. Pol, Jul 14 2011
24 * A280098(n) = A000203(a(n)) if n>0. - Michael Somos, Dec 25 2016
E.g.f.: (24*x-1)*exp(x). - G. C. Greubel, Aug 14 2018
G.f.: (-1 + 25*x)/(1-x)^2. - Wolfdieter Lang, Dec 10 2021
a(n) = 2*A008594(n) - 1. - Leo Tavares, Jun 06 2023

A214360 Primes congruent to 23 modulo 3120613860.

Original entry on oeis.org

23, 3120613883, 6241227743, 9361841603, 12482455463, 15603069323, 18723683183, 21844297043, 24964910903, 28085524763, 34326752483, 43688594063, 62412277223, 115462712843, 124824554423, 156030693023, 159151306883, 171633762323, 180995603903, 196598673203
Offset: 1

Views

Author

Reinhard Zumkeller, Jul 13 2012

Keywords

Comments

A211889(9) = 3120613860;
the first 10 terms constitute row 9 of triangle A211890, an arithmetic progression of 10 primes.

Crossrefs

Cf. A010051.
Sequences of numbers congruent 23 modulo m: A134517 m=24, A141945 m=25, A140375 m=26, A141963 m=27, A141974 m=28, A141999 m=29, A132235 m=30, A142027 m=31, A142044 m=32, A142062 m=33, A142091 m=35, A142107 m=36, A142132 m=37, A142173 m=39, A142192 m=40, A142220 m=41, A142244 m=42, A142272 m=43, A142302 m=44, A142324 m=45, A142374 m=47, A142405 m=48, A142433 m=49, A142490 m=51, A142518 m=52, A142553 m=53, A142617 m=55, A142650 m=56, A142679 m=57, A142750 m=59, A142790 m=60, A142821 m=61, A142902 m=63, A142935 m=64, A140844 m=210.

Programs

  • Haskell
    a214360 n = a214360_list !! (n-1)
    a214360_list = [x | k <- [0..], let x = 3120613860*k+23, a010051' x == 1]
    
  • Maple
    select(isprime,[seq(23+i*3120613860,i=0..1000)]); # Robert Israel, Jun 07 2015
  • Mathematica
    Select[Range[23, 2 10^11, 3120613860], PrimeQ] (* Vincenzo Librandi, Jun 07 2015 *)
  • PARI
    is(n)=isprime(n) && n%3120613860==23 \\ Charles R Greathouse IV, Jul 02 2016

Formula

a(n) ~ 658414080n log n. - Charles R Greathouse IV, Jul 02 2016

A141376 Primes of the form -x^2 + 8*x*y + 8*y^2 (as well as of the form 15*x^2 + 24*x*y + 8*y^2).

Original entry on oeis.org

23, 47, 71, 167, 191, 239, 263, 311, 359, 383, 431, 479, 503, 599, 647, 719, 743, 839, 863, 887, 911, 983, 1031, 1103, 1151, 1223, 1319, 1367, 1439, 1487, 1511, 1559, 1583, 1607, 1823, 1847, 1871, 2039, 2063, 2087, 2111, 2207, 2351, 2399, 2423, 2447, 2543
Offset: 1

Views

Author

Laura Caballero Fernandez, Lourdes Calvo Moguer, Maria Josefa Cano Marquez, Oscar Jesus Falcon Ganfornina and Sergio Garrido Morales (oscfalgan(AT)yahoo.es), Jun 28 2008

Keywords

Comments

Discriminant = +96.
Values of the quadratic form are {0, 8, 12, 15, 20, 23} mod 24, so this is a subsequence of A134517. - R. J. Mathar, Jul 30 2008
Is this the same sequence as A134517?
Substituting 2y = y' gives the quadratic form A141171, so these terms are a subsequence of the terms in A141171. - R. J. Mathar, Jun 10 2020

Examples

			a(2)=47 because we can write 47 = -1^2 + 8*1*2 + 8*2^2 (or 47 = 15*1^2 + 24*1*1 + 8*1^2).
		

References

  • Z. I. Borevich and I. R. Shafarevich, Number Theory.

Crossrefs

Extensions

More terms from Arkadiusz Wesolowski, Jul 25 2012

A138905 a(n) is n-th prime == -1 (mod 6n).

Original entry on oeis.org

5, 23, 71, 167, 179, 431, 461, 863, 863, 839, 1583, 1511, 1949, 2099, 2339, 4127, 4283, 4751, 4673, 4919, 5669, 6599, 8693, 10079, 7349, 10607, 12149, 11087, 12527, 11159, 15809, 19583, 16829, 19583, 13859, 25703, 24197, 25307, 23633, 21839, 34439
Offset: 1

Views

Author

Zak Seidov, Apr 03 2008

Keywords

Examples

			a(1) = 1st term in A007528 (Primes of form 6n-1)
a(2) = 2nd term in A068231 (Primes congruent to 11 (mod 12))
a(3) = 3rd term in A061242 (Primes of form 18n-1)
a(4) = 4th term in A134517 (Primes of form 24n-1)
a(5) = 5th term in A132236 (Primes congruent to 29 (mod 30))
		

Crossrefs

Programs

  • Mathematica
    a[n_]:=Module[{p=1,cnt=0},Until[cnt==n,If[Mod[Prime[p],6n]==6n-1,cnt++];p++];Prime[p-1]];Array[a,41] (* James C. McMahon, Jun 22 2025 *)

A195051 Number of divisors of 24*n - 1.

Original entry on oeis.org

2, 2, 2, 4, 4, 4, 2, 2, 4, 2, 2, 4, 2, 4, 2, 2, 4, 2, 8, 2, 2, 4, 4, 6, 2, 4, 2, 4, 4, 2, 2, 4, 4, 4, 2, 2, 2, 2, 8, 4, 2, 4, 2, 4, 4, 2, 6, 2, 6, 4, 2, 4, 4, 8, 2, 4, 2, 4, 4, 2, 8, 2, 2, 4, 2, 2, 2, 4, 4, 4, 4, 4, 4, 6, 4, 2, 2, 2, 4, 4, 4, 4, 4, 8, 2, 2
Offset: 1

Views

Author

Omar E. Pol, Jan 13 2012

Keywords

Crossrefs

Programs

  • GAP
    List([1..100],n->Tau(24*n-1)); # Muniru A Asiru, Jun 27 2018
    
  • Maple
    seq(numtheory:-tau(24*n-1),n=1..100); # Robert Israel, Jun 27 2018
  • Mathematica
    Table[DivisorSigma[0, 24*n-1], {n, 100}] (* T. D. Noe, Jan 14 2012 *)
  • PARI
    a(n) = numdiv(24*n-1); \\ Amiram Eldar, Dec 22 2023

Formula

a(n) = A000005(A183010(n)).
a(n) = 2 * A195052(n).
Sum_{k=1..n} a(k) ~ (n/3) * (log(n) + 2*gamma - 1 + 5*log(2) + 2*log(3)), where gamma is Euler's constant (A001620). - Amiram Eldar, Dec 22 2023

A195052 Number of divisors of 24*n - 1 divided by 2.

Original entry on oeis.org

1, 1, 1, 2, 2, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 4, 1, 1, 2, 2, 3, 1, 2, 1, 2, 2, 1, 1, 2, 2, 2, 1, 1, 1, 1, 4, 2, 1, 2, 1, 2, 2, 1, 3, 1, 3, 2, 1, 2, 2, 4, 1, 2, 1, 2, 2, 1, 4, 1, 1, 2, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 2, 1, 1, 1, 2, 2, 2, 2, 2, 4, 1, 1
Offset: 1

Views

Author

Omar E. Pol, Jan 13 2012

Keywords

Comments

It appears that this sequence has the same parity as the spt function A092269 (See A195053). - Omar E. Pol, Jan 30 2012

Crossrefs

Programs

  • Mathematica
    a[n_] := DivisorSigma[0, 24*n-1]/2; Array[a, 100] (* Amiram Eldar, Dec 22 2023 *)
  • PARI
    a(n) = numdiv(24*n-1)/2; \\ Amiram Eldar, Dec 22 2023

Formula

a(n) = A000005(A183010(n))/2 = A195051(n)/2.
Sum_{k=1..n} a(k) ~ (n/6) * (log(n) + 2*gamma - 1 + 5*log(2) + 2*log(3)), where gamma is Euler's constant (A001620). - Amiram Eldar, Dec 22 2023

A291900 Sum of the divisors of 24*n - 1, divided by 24, minus n.

Original entry on oeis.org

0, 0, 0, 1, 1, 1, 0, 0, 2, 0, 0, 2, 0, 3, 0, 0, 2, 0, 9, 0, 0, 2, 2, 7, 0, 4, 0, 3, 6, 0, 0, 3, 5, 7, 0, 0, 0, 0, 15, 6, 0, 3, 0, 9, 4, 0, 10, 0, 13, 5, 0, 3, 3, 22, 0, 4, 0, 5, 12, 0, 19, 0, 0, 13, 0, 0, 0, 10, 14, 4, 6, 7, 5, 19, 11, 0, 0, 0, 16, 5, 4, 12, 8, 28, 0, 0, 0, 0, 35, 6, 4, 0, 5, 32, 4, 18, 8, 0, 31, 0
Offset: 1

Views

Author

Omar E. Pol, Nov 02 2017

Keywords

Comments

The indices of the zeros give A131210.

Crossrefs

Programs

  • Mathematica
    a[n_] := DivisorSigma[1, 24 n - 1]/24 - n; Array[a, 90] (* Robert G. Wilson v, Nov 04 2017 *)
  • PARI
    a(n) = sigma(24*n-1)/24 - n; \\ Michel Marcus, Nov 04 2017

Formula

a(n) = sigma(24*n-1)/24 - n = A000203(A183010(n))/24 - n = A280097(n)/24 - n = A280098(n) - n.
Sum_{k=1..n} a(k) = c * n^2 + O(n*log(n)), where c = Pi^2/18 - 1/2 = 0.048311... . - Amiram Eldar, Mar 28 2024

A139527 Numbers n such that numbers 24n+5 are primes.

Original entry on oeis.org

0, 1, 2, 4, 6, 7, 8, 11, 12, 13, 16, 19, 21, 23, 27, 28, 29, 32, 33, 34, 39, 42, 44, 46, 49, 51, 53, 54, 57, 62, 67, 68, 71, 72, 78, 79, 81, 82, 83, 86, 89, 92, 93, 96, 97, 98, 99, 103, 106, 109, 112, 114, 116, 118, 119, 121, 123, 134, 141, 142, 144, 147, 148, 149, 153, 154
Offset: 1

Views

Author

Artur Jasinski, Apr 25 2008

Keywords

Comments

Numbers n such that:
24n+1 is prime see A111174, primes 24n+1 see A107008
24n+5 is prime see A139527, primes 24n+5 see A107003
24n+7 is prime see A139483, primes 24n+7 see A107006
24n+11 is prime A139528, primes 24n+11 see A107007
24n+13 is prime see A139529, primes 24n+13 see A139530
24n+17 is prime see A139531, primes 24n+17 see A107181
24n+19 is prime see A139532, primes 24n+19 see A141373
24n+23 is prime see A131210, primes 24n+23 see A134517

Programs

  • Mathematica
    a = {}; Do[If[PrimeQ[24 n + 5], AppendTo[a, n]], {n, 0, 200}]; a
    Select[Table[(Prime[n]-5)/24,{n,800}],IntegerQ] (* Harvey P. Dale, Feb 25 2016 *)

A207374 Composites of the form 24n - 1.

Original entry on oeis.org

95, 119, 143, 215, 287, 335, 407, 455, 527, 551, 575, 623, 671, 695, 767, 791, 815, 935, 959, 1007, 1055, 1079, 1127, 1175, 1199, 1247, 1271, 1295, 1343, 1391, 1415, 1463, 1535, 1631, 1655, 1679, 1703, 1727, 1751, 1775, 1799, 1895, 1919, 1943, 1967, 1991, 2015
Offset: 1

Views

Author

Omar E. Pol, Feb 18 2012

Keywords

Comments

Also denominators that are composite numbers A002808 in the Bruinier-Ono formula for the partition function (see A183010 and A183011).
The union of A134517 and this sequence gives A183010.

Crossrefs

Programs

Formula

A002808 INTERSECT A183010.

A256397 Primes congruent to {17, 23} mod 24.

Original entry on oeis.org

17, 23, 41, 47, 71, 89, 113, 137, 167, 191, 233, 239, 257, 263, 281, 311, 353, 359, 383, 401, 431, 449, 479, 503, 521, 569, 593, 599, 617, 641, 647, 719, 743, 761, 809, 839, 857, 863, 881, 887, 911, 929, 953, 977, 983, 1031, 1049, 1097, 1103, 1151, 1193
Offset: 1

Views

Author

Arkadiusz Wesolowski, Jun 03 2015

Keywords

Comments

All these primes do not divide any number of the form 2^k + 3. Therefore, they are not in A256396.

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(1193) | p mod 24 in {17, 23}];
    
  • Mathematica
    Select[Prime@Range[196], MemberQ[{17, 23}, Mod[#, 24]] &]
  • PARI
    select(p->my(k=p%24); k==17||k==23, primes(1000)) \\ Charles R Greathouse IV, Jun 03 2015

Formula

Showing 1-10 of 10 results.