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 1-2 of 2 results.

A064544 Biquanimous numbers (or biquams): group the digits into two pieces (not necessarily equal or in order) with the same sum.

Original entry on oeis.org

0, 11, 22, 33, 44, 55, 66, 77, 88, 99, 101, 110, 112, 121, 123, 132, 134, 143, 145, 154, 156, 165, 167, 176, 178, 187, 189, 198, 202, 211, 213, 220, 224, 231, 235, 242, 246, 253, 257, 264, 268, 275, 279, 286, 297, 303, 312, 314, 321, 325, 330, 336, 341, 347, 352, 358
Offset: 0

Views

Author

David W. Wilson, Oct 09 2001

Keywords

Comments

This sequence is 10-automatic (decimal expansions form a regular language accepted by a finite automaton).

Examples

			143 is in the sequence because its digits {1, 4, 3} may be grouped so that 1+3 = 4.
		

Crossrefs

Cf. A064671, A064686 (number of n-digit base-3 biquams), A065023, A065024, A065025.

Programs

  • PARI
    is(n) = { my (d=digits(n), s=[0]); for (k=1, #d, s=setunion(apply(v -> v+d[k], s), apply(v -> v-d[k], s))); setsearch(s, 0)>0 } \\ Rémy Sigrist, Jan 23 2021

A288687 Number of n-digit biquanimous strings using digits {0,1,2,3}.

Original entry on oeis.org

1, 1, 4, 19, 92, 421, 1830, 7687, 31624, 128521, 518666, 2084875, 8361996, 33497101, 134094862, 536608783, 2146926608, 8588754961, 34357248018, 137433710611, 549744803860, 2199000186901, 8796044787734, 35184271425559, 140737278640152, 562949517213721
Offset: 0

Views

Author

Alois P. Heinz, Jun 13 2017

Keywords

Comments

A biquanimous string is a string whose digits can be split into two groups with equal sums.

Crossrefs

Column k=3 of A288638.

Programs

  • Mathematica
    LinearRecurrence[{10,-37,64,-52,16},{1,1,4,19,92,421},30] (* Harvey P. Dale, Jul 29 2017 *)
  • PARI
    Vec((1 - 9*x + 31*x^2 - 48*x^3 + 38*x^4 - 16*x^5) / ((1 - x)^2*(1 - 2*x)^2*(1 - 4*x)) + O(x^30)) \\ Colin Barker, Dec 16 2017

Formula

G.f.: (1 - 9*x + 31*x^2 - 48*x^3 + 38*x^4 - 16*x^5) / ((1 - x)^2*(1 - 2*x)^2*(1 - 4*x)).
a(n) = 1 + A064671(n) for n > 0.
From Colin Barker, Dec 16 2017: (Start)
a(n) = (2^(2*n-1) + n - 2^(n-1)*(1+n)).
a(n) = 10*a(n-1) - 37*a(n-2) + 64*a(n-3) - 52*a(n-4) + 16*a(n-5) for n>5.
(End)
Showing 1-2 of 2 results.