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.

A000148 Number of partitions into non-integral powers.

Original entry on oeis.org

1, 2, 7, 15, 28, 45, 70, 100, 138, 183, 242, 310, 388, 481, 583, 701, 838, 984, 1152, 1337, 1535, 1757, 2001, 2262, 2545, 2855, 3183, 3540, 3926, 4335, 4770, 5233, 5728, 6248, 6801, 7388, 8005, 8658, 9345, 10064, 10824, 11620, 12452, 13324, 14236
Offset: 2

Views

Author

Keywords

Comments

a(n) is the number of solutions to the inequality x_1^(2/3) + x_2^(2/3) <= n where 1 <= x_1 <= x_2 are any two integers. If the number of terms in the sum is not restricted to 2, we get A000234. - R. J. Mathar, Jul 03 2009

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Mathematica
    A000148[n_] := Sum[Min[xi, Floor[(n - xi^(2/3))^(3/2)]], {xi, 1, Floor[n^(3/2)]}];
    Table[A000148[n], {n, 2, 100}] (* Seth A. Troisi, May 25 2022 *)

Extensions

More terms from Sean A. Irvine, Oct 08 2009

A000327 Number of partitions into non-integral powers.

Original entry on oeis.org

1, 5, 12, 23, 39, 62, 91, 127, 171, 228, 294, 370, 461, 561, 677, 811, 955, 1121, 1303, 1499, 1719, 1960, 2218, 2499, 2806, 3131, 3485, 3868, 4274, 4706, 5166, 5658, 6175, 6725, 7309, 7923, 8572, 9256, 9972, 10728, 11521, 12349, 13218, 14126, 15072
Offset: 3

Views

Author

Keywords

Comments

a(n) counts the solutions to the inequality x_1^(2/3) + x_2^(2/3) <= n for any two distinct integers 1 <= x_1 < x_2. - R. J. Mathar, Jul 03 2009

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Maple
    A000327 := proc(n) local a,x1,x2 ; a := 0 ; for x1 from 1 to floor(n^(3/2)) do x2 := (n-x1^(2/3))^(3/2) ; if floor(x2) >= x1+1 then a := a+floor(x2-x1) ; fi; od: a ; end: seq(A000327(n),n=3..80) ; # R. J. Mathar, Sep 29 2009
  • Mathematica
    A000327[n_] := Module[{a, x1, x2 }, a = 0; For[x1 = 1, x1 <= Floor[ n^(3/2)], x1++, x2 = (n - x1^(2/3))^(3/2); If[Floor[x2] >= x1+1, a = a + Floor[x2 - x1]]]; a ]; Table[A000327[n], {n, 3, 80}] (* Jean-François Alcover, Feb 07 2016, after R. J. Mathar *)
    A000327[n_] := Sum[Min[x1 - 1, Floor[(n - x1^(2/3))^(3/2)]], {x1, 2, Floor[n^(3/2)]}];
    Table[A000327[n], {n, 3, 80}] (* Seth A. Troisi, May 25 2022 *)

Formula

a(n) = A000148(n) - floor((n/2)^(3/2)). - Seth A. Troisi, May 25 2022

Extensions

More terms from R. J. Mathar, Sep 29 2009

A000135 Number of partitions into non-integral powers.

Original entry on oeis.org

1, 2, 6, 13, 24, 42, 73, 125, 204, 324, 511, 801, 1228, 1856, 2780, 4135, 6084, 8873, 12847, 18481, 26416, 37473, 52871, 74216, 103596, 143841, 198839, 273654, 374987, 511735, 695559, 941932, 1271139, 1709474, 2291195, 3061385, 4078152, 5416322
Offset: 1

Views

Author

Keywords

Comments

a(n) counts the solutions to the inequality sum_{i=1,2,..} x_i^(2/3)<=n for any number of distinct integers 1<=x_1R. J. Mathar, Jul 03 2009

Examples

			For n=3, the 6 solutions are (i) 1^(2/3)<=3. (ii) 1^(2/3)+2^(2/3)<=3. (iii) 2^(2/3)<=3. (iv) 3^(2/3)<=3. (v) 4^(2/3)<=3. (vi) 5^(2/3)<=3. - _R. J. Mathar_, Jul 03 2009
		

References

  • B. K. Agarwala and F. C. Auluck, Statistical mechanics and partitions into non-integral powers of integers, Proc. Camb. Phil. Soc., 47 (1951), 207-216.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Extensions

8 more terms from R. J. Mathar, Jul 03 2009
20 more terms from Sean A. Irvine, Sep 28 2009

A259447 Triangle read by rows arising from enumeration of partitions into non-integral powers.

Original entry on oeis.org

1, 2, 1, 5, 2, 1, 8, 7, 2, 1, 11, 15, 8, 2, 1, 14, 28, 19, 8, 2, 1, 18, 45, 41, 21, 8, 2, 1, 22, 70, 78, 48, 22, 8, 2, 1, 27, 100, 134, 99, 52, 22, 8, 2, 1, 31, 138, 218, 186, 111, 53, 22, 8, 2, 1
Offset: 1

Views

Author

N. J. A. Sloane, Jun 27 2015

Keywords

Examples

			Triangle begins:
1,
2,1,
5,2,1,
8,7,2,1,
11,15,8,2,1,
14,28,19,8,2,1,
18,45,41,21,8,2,1,
22,70,78,48,22,8,2,1,
27,100,134,99,52,22,8,2,1,
31,138,218,186,111,53,22,8,2,1,
...
		

Crossrefs

Columns include A000093, A000148, A000158, A000169.
Showing 1-4 of 4 results.