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 1-3 of 3 results.

A080119 Positions of A080118 in A014486.

Original entry on oeis.org

1, 2, 7, 33, 81, 74395, 8369196, 215802898, 414859094165, 520973680640109, 4064761999842441067, 517978450857911919447, 4255027826896017770661, 5222501054779098990032001033, 718000720375918750838217734094612383
Offset: 1

Views

Author

Antti Karttunen, Feb 11 2003

Keywords

Programs

Formula

a(n) = A215406(A080118(n)). - Peter Luschny, Aug 10 2012

A080117 Binary encoding of quadratic residue set formed for n-th prime, coerced to "complementarily symmetric binary sequence" with A080261 if the prime is of the form 4k+1.

Original entry on oeis.org

2, 10, 52, 738, 2866, 53620, 162438, 4023888, 166243974, 921787428, 48034443442, 935251508324, 2558696229078, 68055676507664, 2655011787909270, 210067141980993186, 831463106366605026, 42882922858578320598
Offset: 2

Views

Author

Antti Karttunen, Feb 11 2003

Keywords

Crossrefs

Programs

  • Maple
    with(numtheory,ithprime); A080117 := proc(n) local c,p; p := ithprime(n); c := A055094(p); if(3 = (p mod 4)) then RETURN(c); else RETURN(A080261(c)); fi; end;
  • Mathematica
    A055094[n_] := With[{rr = Table[Mod[k^2, n], {k, 1, n-1}] // Union}, Boole[ MemberQ[rr, #]] & /@ Range[n-1]] // FromDigits[#, 2]&;
    A080261[n_] := Module[{bb = IntegerDigits[n, 2]}, lg = Length[bb]; Do[ bb[[i]] = 1 - bb[[i]], {i, lg, lg - Floor[lg/2] + 1, -1}]; FromDigits[ bb, 2]];
    a[n_] := Module[{c, p = Prime[n]}, c = A055094[p]; If[Mod[p, 4] == 3, c, A080261[c]]]; Table[a[n], {n, 2, 20}] (* Jean-François Alcover, Mar 05 2016, adapted from Maple *)
  • Sage
    # uses[A080261]
    def A080117(n) :
        p = nth_prime(n)
        c = A055094(p)
        return c if 3 == p%4 else A080261(c)
    [A080117(n) for n in (2..19)] # Peter Luschny, Aug 09 2012

Formula

a(A080148(n)) = A080146(A080148(n))

A080120 Dyck path encodings of Legendre's candelabras formed for primes in A080114. (I.e., symmetric rooted plane trees constructed from their quadratic residue sets.)

Original entry on oeis.org

10, 1010, 110100, 1011100010, 101100110010, 1111010110011001010000, 110110111100010101110000100100, 101100101111000100110111000010110010, 1111011110010101110010011011000101011000010000
Offset: 1

Views

Author

Antti Karttunen, Feb 11 2003

Keywords

Comments

For the 2nd, 5th and 8th term of the sequence, the quadratic residue set of the corresponding prime (5,13,37, of the form 4k+1) has been converted from symmetric to complementarily symmetric as 1001->1010, 101100001101->101100110010, 101100101111000100001000111101001101->101100101111000100110111000010110010, for the others (of the form 4k+3), it is the quadratic residue set encoded as in A055094 (with +1 mapped to 1 and -1 to 0).

Crossrefs

Same sequence in decimal: A080118. Cf. A080114.

Programs

Formula

a(n) = A063171(A080119(n)).
Showing 1-3 of 3 results.