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 1-5 of 5 results.

A096629 Values of n for which {p_3, p_4, ..., p_n} (mod 3) contains equal numbers of 1's and 2's.

Original entry on oeis.org

4, 6, 8, 12, 14, 22, 38, 48, 50, 23338590786, 23338590788, 23338590790, 23338590806, 23338590808, 23338590820, 23338590822, 23338590824, 23338590826, 23338590828, 23338590830, 23338590834, 23338590840, 23338590858, 23338590860, 23338590868, 23338590870
Offset: 1

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Author

Eric W. Weisstein, Jul 04 2004

Keywords

Crossrefs

Formula

a(n) = A000720(A098044(n+1)).

Extensions

Edited by Max Alekseyev, Sep 13 2009
Terms a(10) onward from Max Alekseyev, Feb 10 2011

A297006 Primes p for which pi_{3,2}(p) - pi_{3,1}(p) = -1, where pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

Original entry on oeis.org

608981813029, 608981813137, 608981813261, 608981813273, 608981813311, 608981813357, 608981813459, 608981813683, 608981813717, 608981813777, 608981813789, 608981814127, 608981818999, 608981819021, 608981819273, 608981819359, 608981819419, 608981820869, 608981820899, 608981820913, 608981826877, 608981827873, 608981827891, 608981828023, 608981828029, 608981828111, 608981828129, 608981836363, 608981836391, 608981836481
Offset: 1

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Author

Andrey S. Shchebetov and Sergei D. Shchebetov, Dec 23 2017

Keywords

Comments

This sequence is a companion sequence to A297005. Starting from a(20591)=6148171711663 the sequence includes the second sign-changing zone predicted by C. Bays et al. in 2001. The sequence with the first two sign-changing zones up to 10^13 contains 84323 terms with a(84323)=6156051951677 as its last term (see b-file). In addition, a(1) = A007352(2) as well as a(20591) = A007352(9630).

Crossrefs

A297005 Values of n for which pi_{3,2}(p_n) - pi_{3,1}(p_n) = -1, where p_n is the n-th prime and pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

Original entry on oeis.org

23338590792, 23338590794, 23338590796, 23338590798, 23338590800, 23338590802, 23338590804, 23338590810, 23338590814, 23338590816, 23338590818, 23338590832, 23338591016, 23338591018, 23338591028, 23338591030, 23338591032, 23338591084, 23338591086, 23338591088, 23338591302, 23338591340, 23338591342, 23338591344, 23338591346, 23338591348, 23338591350, 23338591656, 23338591658, 23338591662
Offset: 1

Views

Author

Andrey S. Shchebetov and Sergei D. Shchebetov, Dec 23 2017

Keywords

Comments

This sequence is a companion sequence to A297006. Starting from a(20591)=216415270060 the sequence includes the second sign-changing zone predicted by C. Bays et al. in 2001. The sequence with the first two sign-changing zones up to 10^13 contains 84323 terms with a(84323)=216682882512 as its last term (see b-file). In addition, a(1) = A096630(1).

Crossrefs

A174695 Partial sums of A173950.

Original entry on oeis.org

0, 0, 1, 0, 1, 0, 1, 0, 1, 2, 1, 0, 1, 0, 1, 2, 3, 2, 1, 2, 1, 0, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 3, 2, 3, 2, 1, 0, 1, 2, 3, 2, 3, 2, 3, 2, 1, 0, 1, 0, 1, 2, 1, 2, 3, 4, 5, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 2, 3, 2, 3, 4, 3, 2, 1, 2, 3, 2
Offset: 1

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Author

Giovanni Teofilatto, Nov 30 2010

Keywords

Comments

Since this sequence equals A112632(n)-1, and A007352 gives the primes at which the sign of A112632 changes, we have a change of sign in the present sequence not exactly at the primes listed in A007352, but earlier for changes to negative sign, and later for the opposite changes. Moreover, a change of sign in either of the sequences corresponds not necessarily to a change of sign (in the strict sense, i.e., regarding 0 as a number with the same sign as the preceding term) in the other one. - M. F. Hasler, Oct 09 2011

Crossrefs

Concerning zeros or changes of sign, see also A096449 and A275939.

Programs

  • Maple
    A173950 := proc(n) if (ithprime(n)+1) mod 6 = 0 then 1; elif (ithprime(n)-1) mod 6 = 0 then -1; else 0 ; end if; end proc:
    A174695 := proc(n) add(A173950(i),i=1..n) ; end proc:
    seq(A174695(n),n=1..90) ; # R. J. Mathar, Nov 30 2010
  • Mathematica
    Accumulate[Table[Which[Divisible[Prime[n]+1,6],1,Divisible[Prime[n]-1,6],-1,True,0],{n,150}]] (* Harvey P. Dale, Apr 24 2019 *)
  • PARI
    s=0;forprime(p=1,999,print1(s+=if(p%3-1,p>3,-1)","))  \\ M. F. Hasler, Oct 09 2011

Formula

a(n) = A112632(n)-1. - M. F. Hasler, Oct 09 2011

A306891 Primes p for which pi_{3,2}(p) < pi_{3,1}(p), where pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

Original entry on oeis.org

608981813029, 608981813137, 608981813191, 608981813261, 608981813269, 608981813273, 608981813311, 608981813347, 608981813357, 608981813449, 608981813459, 608981813683, 608981813701, 608981813707, 608981813711, 608981813717, 608981813719, 608981813777, 608981813779
Offset: 1

Views

Author

Jianing Song, Mar 16 2019

Keywords

Comments

Primes p such that Sum_{primes q <= p} Kronecker(-3,q) > 0.
Indices of negative terms in A321856. See also the comment about Chebyshev's bias in A321856.

Crossrefs

Programs

  • PARI
    my(i=0); forprime(p=608981813029, 608981820000, i+=kronecker(-3, p); if(i>0, print1(p, ", ")))

Formula

a(n) = prime(A096630(n)).
Showing 1-5 of 5 results.