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 1-4 of 4 results.

A065730 Largest square <= n-th prime.

Original entry on oeis.org

1, 1, 4, 4, 9, 9, 16, 16, 16, 25, 25, 36, 36, 36, 36, 49, 49, 49, 64, 64, 64, 64, 81, 81, 81, 100, 100, 100, 100, 100, 121, 121, 121, 121, 144, 144, 144, 144, 144, 169, 169, 169, 169, 169, 196, 196, 196, 196, 225, 225, 225, 225, 225, 225, 256, 256, 256, 256, 256
Offset: 1

Views

Author

Labos Elemer, Nov 15 2001

Keywords

Comments

For n > 2: a(n) = A257053(n,0). - Reinhard Zumkeller, Apr 15 2015

Crossrefs

Programs

Formula

a(n) = A048760(A000040(n)).

A256913 Enhanced squares representations for k = 0, 1, 2, ..., concatenated.

Original entry on oeis.org

0, 1, 2, 3, 4, 4, 1, 4, 2, 4, 3, 4, 3, 1, 9, 9, 1, 9, 2, 9, 3, 9, 4, 9, 4, 1, 9, 4, 2, 16, 16, 1, 16, 2, 16, 3, 16, 4, 16, 4, 1, 16, 4, 2, 16, 4, 3, 16, 4, 3, 1, 25, 25, 1, 25, 2, 25, 3, 25, 4, 25, 4, 1, 25, 4, 2, 25, 4, 3, 25, 4, 3, 1, 25, 9, 25, 9, 1, 36
Offset: 0

Views

Author

Clark Kimberling, Apr 14 2015

Keywords

Comments

Let B = {0,1,2,3,4,9,16,25,...}, so that B consists of the squares together with 2 and 3. We call B the enhanced basis of squares. Define R(0) = 0 and R(n) = g(n) + R(n - g(n)) for n > 0, where g(n) is the greatest number in B that is <= n. Thus, each n has an enhanced squares representation of the form R(n) = b(m(n)) + b(m(n-1)) + ... + b(m(k)), where b(n) > m(n-1) > ... > m(k) > 0, in which the last term, b(m(k)), is the trace.
The least n for which R(n) has 5 terms is given by R(168) = 144 + 16 + 4 + 3 + 1.
The least n for which R(n) has 6 terms is given by R(7224) = 7056 + 144 + 16 + 4 + 3 + 1.

Examples

			R(0) = 0
R(1) = 1
R(2) = 2
R(3) = 3
R(4) = 4
R(8) = 4 + 3 + 1
R(24) = 16 + 4 + 3 + 1
		

Crossrefs

Cf. A000290, A256914 (trace), A256915 (number of terms), A256789 (minimal alternating squares representations).
Cf. A257053 (primes).

Programs

  • Haskell
    a256913 n k = a256913_tabf !! n !! k
    a256913_row n = a256913_tabf !! n
    a256913_tabf = [0] : tail esr where
       esr = (map r [0..8]) ++
               f 9 (map fromInteger $ drop 3 a000290_list) where
         f x gs@(g:hs@(h:_))
           | x < h   = (g : genericIndex esr (x - g)) : f (x + 1) gs
           | otherwise = f x hs
         r 0 = []; r 8 = [4, 3, 1]
         r x = q : r (x - q) where q = [0,1,2,3,4,4,4,4,4] !! x
    -- Reinhard Zumkeller, Apr 15 2015
  • Mathematica
    b[n_] := n^2; bb = Insert[Table[b[n], {n, 0, 100}]  , 2, 3];
    s[n_] := Table[b[n], {k, 1, 2 n + 1}];
    h[1] = {0, 1, 2, 3}; h[n_] := Join[h[n - 1], s[n]];
    g = h[100]; Take[g, 100]
    r[0] = {0}; r[1] = {1}; r[2] = {2}; r[3] = {3}; r[8] = {4, 3, 1};
    r[n_] := If[MemberQ[bb, n], {n}, Join[{g[[n]]}, r[n - g[[n]]]]];
    t = Table[r[n], {n, 0, 120}] (* A256913, before concatenation *)
    Flatten[t]  (* A256913 *)
    Table[Last[r[n]], {n, 0, 120}]    (* A256914 *)
    Table[Length[r[n]], {n, 0, 200}]  (* A256915 *)

A257070 Traces of primes in enhanced squares representation, cf. A256913.

Original entry on oeis.org

2, 3, 1, 3, 2, 4, 1, 3, 3, 4, 2, 1, 1, 3, 2, 4, 1, 3, 3, 3, 9, 2, 2, 1, 16, 1, 3, 3, 9, 4, 2, 1, 16, 2, 1, 3, 4, 3, 3, 4, 1, 3, 2, 1, 1, 3, 2, 2, 2, 4, 1, 1, 16, 1, 1, 3, 4, 2, 1, 25, 2, 4, 2, 2, 1, 3, 3, 4, 3, 25, 4, 1, 2, 3, 2, 2, 3, 36, 1, 9, 3, 1, 2, 1
Offset: 1

Views

Author

Reinhard Zumkeller, Apr 15 2015

Keywords

Comments

a(n) = A256914(A000040(n)).

Crossrefs

Programs

  • Haskell
    a257070 = last . a257053_row

A257071 Length of enhanced squares representation of n-th prime, cf. A256913.

Original entry on oeis.org

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

Views

Author

Reinhard Zumkeller, Apr 15 2015

Keywords

Comments

a(n) = A256915(A000040(n)).

Crossrefs

Programs

  • Haskell
    a257071 = length . a257053_row
Showing 1-4 of 4 results.