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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A035208 Coefficients in expansion of Dirichlet series Product_p (1-(Kronecker(m,p)+1)*p^(-s)+Kronecker(m,p)*p^(-2s))^(-1) for m = 26.

Original entry on oeis.org

1, 1, 0, 1, 2, 0, 0, 1, 1, 2, 2, 0, 1, 0, 0, 1, 2, 1, 2, 2, 0, 2, 2, 0, 3, 1, 0, 0, 0, 0, 0, 1, 0, 2, 0, 1, 2, 2, 0, 2, 0, 0, 0, 2, 2, 2, 0, 0, 1, 3, 0, 1, 0, 0, 4, 0, 0, 0, 2, 0, 0, 0, 0, 1, 2, 0, 2, 2, 0, 0, 0, 1, 0, 2, 0, 2, 0, 0, 2, 2, 1
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := DivisorSum[n, KroneckerSymbol[26, #] &]; Array[a, 100] (* Amiram Eldar, Nov 19 2023 *)
  • PARI
    my(m = 26); direuler(p=2,101,1/(1-(kronecker(m,p)*(X-X^2))-X))
    
  • PARI
    a(n) = sumdiv(n, d, kronecker(26, d)); \\ Amiram Eldar, Nov 19 2023

Formula

From Amiram Eldar, Nov 19 2023: (Start)
a(n) = Sum_{d|n} Kronecker(26, d).
Multiplicative with a(p^e) = 1 if Kronecker(26, p) = 0 (p = 2 or 13), a(p^e) = (1+(-1)^e)/2 if Kronecker(26, p) = -1 (p is in A038900), and a(p^e) = e+1 if Kronecker(26, p) = 1 (p is in A038899 \ {2, 13}).
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = 2*log(sqrt(26)+5)/sqrt(26) = 0.907012940471... . (End)

A378295 Prime norms of ideals in Q(sqrt(10), sqrt(26)).

Original entry on oeis.org

2, 5, 13, 37, 67, 79, 83, 163, 191, 197, 199, 227, 293, 307, 311, 317, 397, 439, 521, 557, 569, 587, 599, 601, 613, 641, 643, 683, 719, 733, 751, 773, 787, 809, 827, 853, 877, 881, 911, 919, 947, 991, 1031, 1039, 1049, 1123, 1163, 1231, 1237, 1249, 1307, 1361, 1373, 1439, 1481, 1493
Offset: 1

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Author

Jovan Radenkovicc, Nov 22 2024

Keywords

Comments

Except for 2, 5 and 13, primes congruent to 1, 9, 37, 49, 67, 79, 81, 83, 93, 121, 123, 129, 159, 163, 187, 191, 197, 199, 203, 209, 213, 227, 231, 253, 267, 289, 293, 307, 311, 317, 321, 323, 329, 333, 357, 361, 391, 397, 399, 427, 437, 439, 441, 453, 471, 483, 511, 519 mod 520.
Primes in A378294.
Every prime p occurs in exactly one or all three of the sequences A038879, A038899 and A038945. This sequence lists the primes appearing in all three sequences.

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(1500) | p in {2, 5, 13} or p mod 520 in [1, 9, 37, 49, 67, 79, 81, 83, 93, 121, 123, 129, 159, 163, 187, 191, 197, 199, 203, 209, 213, 227, 231, 253, 267, 289, 293, 307, 311, 317, 321, 323, 329, 333, 357, 361, 391, 397, 399, 427, 437, 439, 441, 453, 471, 483, 511, 519]];
Showing 1-2 of 2 results.