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 1-7 of 7 results.

A353918 a(n) is the number of ways to write n as a sum of distinct terms of A353889.

Original entry on oeis.org

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

Views

Author

Rémy Sigrist, May 11 2022

Keywords

Comments

a(0) = 1 accounts for the empty sum.

Examples

			The first terms, alongside the corresponding subsets of A353889, are:
  n   a(n)  Corresponding subsets
  --  ----  ---------------------
   0     1  {}
   1     0  none
   2     0  none
   3     1  {3}
   4     0  none
   5     0  none
   6     1  {6}
   7     0  none
   8     0  none
   9     2  {3, 6}, {9}
  10     0  none
  11     1  {11}
  12     1  {3, 9}
		

Crossrefs

Cf. A353889, A353919 (positions of 0's).

A353919 Numbers that are not the sum of distinct terms of A353889.

Original entry on oeis.org

1, 2, 4, 5, 7, 8, 10, 13, 16, 21, 32, 40, 51, 56, 59, 64, 128, 133, 251, 256, 320, 325, 512, 517, 827, 832, 1019, 1024, 2048, 2053, 2555, 2560, 4091, 4096, 6656, 6661, 8192, 8197, 16379, 16384, 20480, 20485, 32768, 32773, 53243, 53248, 65531, 65536, 131072
Offset: 1

Views

Author

Rémy Sigrist, May 11 2022

Keywords

Comments

Also positions of 0's in A353918.
This sequence is infinite as it contains the powers of 2 (A000079).

Examples

			A353918(51) = 0, so 51 belongs to this sequence.
		

Crossrefs

A353966 Lexicographically earliest sequence of distinct positive integers with no finite subset summing to a positive Fibonacci number.

Original entry on oeis.org

4, 6, 10, 12, 19, 25, 40, 62, 110, 178, 288, 466, 576, 644, 754, 1974, 2152, 2262, 3948, 8362, 11556, 15504, 35422, 43784, 48342, 66286, 150050, 198392, 209948, 467861, 896352, 1357215, 2191229, 4389456, 8351641, 11405774, 18454930, 29860704, 48315634
Offset: 1

Views

Author

Rémy Sigrist, May 12 2022

Keywords

Comments

The sequence is well defined:
- a(1) = 4,
- for n > 0, let k be such that A000045(k) + 1 + a(1) + ... + a(n) < A000045(k+1),
- then a(n+1) <= A000045(k) + 1.

Crossrefs

See A353889 for similar sequences.

A353969 Lexicographically earliest sequence of distinct positive integers with no finite subset summing to a factorial number (A000142).

Original entry on oeis.org

3, 4, 5, 7, 11, 18, 22, 23, 25, 26, 96, 103, 107, 114, 118, 158, 600, 696, 703, 707, 714, 718, 782, 4320, 4920, 5016, 5023, 5027, 5034, 5038, 5222, 35280, 39600, 40200, 40296, 40303, 40307, 40314, 40318, 41222, 322560, 357840, 362160, 362760, 362856, 362863
Offset: 1

Views

Author

Rémy Sigrist, May 12 2022

Keywords

Comments

The sequence is well defined:
- a(1) = 3,
- for n > 0, let k be such that A000142(k) + 1 + a(1) + ... + a(n) < A000142(k+1),
- then a(n+1) <= A000142(k) + 1.

Crossrefs

See A353889 for similar sequences.

A353983 Lexicographically earliest sequence of distinct positive integers with no finite subset summing to a Catalan number (A000108).

Original entry on oeis.org

3, 4, 6, 9, 12, 13, 28, 31, 34, 59, 62, 65, 90, 145, 297, 328, 673, 1001, 1298, 2134, 3432, 4433, 7501, 11934, 15366, 26624, 41990, 53924, 95302, 149226, 191216, 343672, 534888, 684114, 1247426, 1931540, 2466428, 4553977, 7020405, 8951945, 16710880, 25662825
Offset: 1

Views

Author

Rémy Sigrist, May 13 2022

Keywords

Comments

The sequence is well defined:
- a(1) = 3,
- for n > 0, let k be such that A000108(k) + 1 + a(1) + ... + a(n) < A000108(k+1),
- then a(n+1) <= A000108(k) + 1.

Crossrefs

See A353889 for similar sequences.

A354005 Lexicographically earliest sequence of distinct positive integers with no finite subset summing to a positive Pell number (A000129).

Original entry on oeis.org

3, 4, 6, 7, 10, 11, 17, 24, 41, 58, 99, 116, 140, 239, 280, 338, 577, 816, 1393, 1970, 3363, 3940, 4756, 8119, 9512, 11482, 19601, 27720, 47321, 66922, 114243, 133844, 161564, 275807, 323128, 390050, 665857, 941664, 1607521, 2273378, 3880899, 4546756, 5488420
Offset: 1

Views

Author

Rémy Sigrist, May 13 2022

Keywords

Comments

The sequence is well defined:
- a(1) = 3,
- for n > 0, let k be such that A000129(k) + 1 + a(1) + ... + a(n) < A000129(k+1),
- then a(n+1) <= A000129(k) + 1.

Crossrefs

See A353889 for similar sequences.

A363245 Lexicographically first sequence of positive integers such that all terms are pairwise coprime and no subset sum is a power of 2.

Original entry on oeis.org

3, 7, 10, 11, 17, 31, 41, 71, 169, 199, 263, 337, 367, 1553, 2129, 2287, 2297, 4351, 10433, 16391, 16433, 34829, 65543, 69557, 165887, 262151, 358481, 817153, 952319, 1048583, 3704737, 3932167, 4518071, 12582919, 17305417, 17367019, 50069497, 50593799, 87228517
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A353889.

Programs

  • Mathematica
    a = {3}; k = 2; Monitor[Do[While[Or[! Apply[CoprimeQ, Join[a, {k}]], AnyTrue[Map[Log2 @* Total@ Append[#, k] &, Subsets[a]], IntegerQ]], k++]; AppendTo[a, k]; k++, {i, 16}], {i, k}]; a (* Michael De Vlieger, Jun 14 2023 *)
  • Python
    from math import gcd
    from itertools import count, islice
    def agen(): # generator of terms
        a, ss, pows2, m = [], set(), {1, 2}, 2
        for k in count(1):
            if k in pows2: continue
            elif k > m: m <<= 1; pows2.add(m)
            if any(p2-k in ss for p2 in pows2): continue
            if any(gcd(ai, k) != 1 for ai in a): continue
            a.append(k); yield k
            ss |= {k} | {k+si for si in ss if k+si not in ss}
            while m < max(ss): m <<= 1; pows2.add(m)
    print(list(islice(agen(), 30))) # Michael S. Branicky, Jun 09 2023

Extensions

a(23)-a(33) from Michael S. Branicky, Jun 07 2023
a(34)-a(39) from Jon E. Schoenfield, Jun 09 2023
Showing 1-7 of 7 results.