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 1-10 of 10 results.

A352089 Tribonacci-Niven numbers: numbers that are divisible by the number of terms in their minimal (or greedy) representation in terms of the tribonacci numbers (A278038).

Original entry on oeis.org

1, 2, 4, 6, 7, 8, 12, 13, 14, 18, 20, 21, 24, 26, 27, 28, 30, 33, 36, 39, 40, 44, 46, 48, 56, 60, 68, 69, 72, 75, 76, 80, 81, 82, 84, 87, 88, 90, 94, 96, 100, 108, 115, 116, 120, 126, 128, 129, 132, 135, 136, 138, 140, 149, 150, 156, 162, 168, 174, 176, 177, 180
Offset: 1

Views

Author

Amiram Eldar, Mar 04 2022

Keywords

Comments

Numbers k such that A278043(k) | k.
The positive tribonacci numbers (A000073) are all terms.
If k = A000073(A042964(m)) is an odd tribonacci number, then k+1 is a term.
Ray (2005) and Ray and Cooper (2006) called these numbers "3-Zeckendorf Niven numbers" and proved that their asymptotic density is 0. - Amiram Eldar, Sep 06 2024

Examples

			6 is a term since its minimal tribonacci representation, A278038(6) = 110, has A278043(6) = 2 1's and 6 is divisible by 2.
		

References

  • Andrew B. Ray, On the natural density of the k-Zeckendorf Niven numbers, Ph.D. dissertation, Central Missouri State University, 2005.

Crossrefs

Programs

  • Mathematica
    t[1] = 1; t[2] = 2; t[3] = 4; t[n_] := t[n] = t[n - 1] + t[n - 2] + t[n - 3]; q[n_] := Module[{s = {}, m = n, k}, While[m > 0, k = 1; While[t[k] <= m, k++]; k--; AppendTo[s, k]; m -= t[k]; k = 1]; Divisible[n, DigitCount[Total[2^(s - 1)], 2, 1]]]; Select[Range[180], q]

A352090 Numbers k such that k and k+1 are both tribonacci-Niven numbers (A352089).

Original entry on oeis.org

1, 6, 7, 12, 13, 20, 26, 27, 39, 68, 75, 80, 81, 87, 115, 128, 135, 149, 176, 184, 185, 195, 204, 215, 224, 230, 236, 243, 264, 278, 284, 291, 344, 364, 399, 447, 506, 507, 519, 548, 555, 560, 575, 595, 615, 635, 656, 664, 665, 684, 704, 725, 744, 777, 804, 824
Offset: 1

Views

Author

Amiram Eldar, Mar 04 2022

Keywords

Comments

Numbers k such that A278043(k) | k and A278043(k+1) | k+1.
The odd tribonacci numbers, A000073(A042964(m)), are all terms.

Examples

			6 is a term since 6 and 7 are both tribonacci-Niven numbers: the minimal tribonacci representation of 6, A278038(6) = 110, has 2 1's and 6 is divisible by 2, and the minimal tribonacci representation of 7, A278038(7) = 1000, has one 1 and 7 is divisible by 1.
		

Crossrefs

Programs

  • Mathematica
    t[1] = 1; t[2] = 2; t[3] = 4; t[n_] := t[n] = t[n - 1] + t[n - 2] + t[n - 3]; q[n_] := Module[{s = {}, m = n, k}, While[m > 0, k = 1; While[t[k] <= m, k++]; k--; AppendTo[s, k]; m -= t[k]; k = 1]; Divisible[n, DigitCount[Total[2^(s - 1)], 2, 1]]]; Select[Range[1000], q[#] && q[# + 1] &]

A352091 Starts of runs of 3 consecutive tribonacci-Niven numbers (A352089).

Original entry on oeis.org

6, 12, 26, 80, 184, 506, 664, 1602, 1603, 1704, 3409, 6034, 9830, 15723, 16744, 19088, 21230, 21664, 22834, 33544, 39424, 40662, 40730, 51190, 55744, 56224, 60710, 61264, 63734, 66014, 66055, 67144, 67248, 73024, 78064, 81150, 84790, 94086, 95094, 109087, 111880
Offset: 1

Views

Author

Amiram Eldar, Mar 04 2022

Keywords

Examples

			6 is a term since 6, 7 and 8 are all tribonacci-Niven numbers: the minimal tribonacci representation of 6, A278038(6) = 110, has 2 1's and 6 is divisible by 2, the minimal tribonacci representation of 7, A278038(7) = 1000, has one 1 and 7 is divisible by 1, and the minimal tribonacci representation of 8, A278038(8) = 1001, has 2 1's and 8 is divisible by 2.
		

Crossrefs

Cf. A278038.
Subsequence of A352089 and A352090.
A352092 is a subsequence.

Programs

  • Mathematica
    t[1] = 1; t[2] = 2; t[3] = 4; t[n_] := t[n] = t[n - 1] + t[n - 2] + t[n - 3]; triboNivenQ[n_] := Module[{s = {}, m = n, k}, While[m > 0, k = 1; While[t[k] <= m, k++]; k--; AppendTo[s, k]; m -= t[k]; k = 1]; Divisible[n, DigitCount[Total[2^(s - 1)], 2, 1]]]; seq[count_, nConsec_] := Module[{tri = triboNivenQ /@ Range[nConsec], s = {}, c = 0, k = nConsec + 1}, While[c < count, If[And @@ tri, c++; AppendTo[s, k - nConsec]]; tri = Join[Rest[tri], {triboNivenQ[k]}]; k++]; s]; seq[30, 3]

A352110 Starts of runs of 4 consecutive lazy-tribonacci-Niven numbers (A352107).

Original entry on oeis.org

1081455, 1976895, 2894175, 5886255, 6906912, 15604110, 16588752, 19291479, 20387232, 25919439, 32394942, 34801557, 35654175, 36813582, 36907899, 39117219, 41407392, 43520832, 46181055, 47954499, 52145952, 54524319, 54815397, 56733639, 57775102, 58942959, 59292177
Offset: 1

Views

Author

Amiram Eldar, Mar 05 2022

Keywords

Comments

Conjecture: There are no runs of 5 consecutive lazy-tribonacci-Niven numbers (checked up to 6*10^9).

Examples

			1081455 is a term since 1081455, 1081456, 1081457 and 1081458 are all divisible by the number of terms in their maximal tribonacci representation:
        k               A352103(k)   A352104(k)    k/A352104(k)
  -------  -----------------------   ----------    ------------
  1081455  10101011011110110011110           15           72097
  1081456  10101011011110110011111           16           67591
  1081457  10101011011110110100100           13           83189
  1081458  10101011011110110100101           14           77247
		

Crossrefs

Subsequence of A352107, A352108 and A352109.

A352345 Starts of runs of 4 consecutive lazy-Pell-Niven numbers (A352342).

Original entry on oeis.org

750139, 41765247, 54831951, 56423275, 136038447, 151175724, 223956843, 227483124, 293913170, 362557214, 382572475, 457616575, 502106253, 562407324, 586380624, 637133390, 724382239, 771849439, 774421478, 859463253, 926398647, 953750523, 1043787390, 1193063550
Offset: 1

Views

Author

Amiram Eldar, Mar 12 2022

Keywords

Comments

Conjecture: There are no runs of 5 consecutive lazy-Pell-Niven numbers (checked up to 10^9).

Examples

			750139 is a term since 750139, 750140, 750141 and 750142 are all divisible by the sum of the digits in their maximal Pell representation:
       k        A352339(k)  A352340(k)  k/A352340(k)
  ------  ----------------  ---------   -----------
  750139  1102022021112220         19         39481
  750140  1102022021112221         20         37507
  750141  1102022021112222         21         35721
  750142  1102022021120210         17         44126
		

Crossrefs

A352511 Starts of runs of 4 consecutive Catalan-Niven numbers (A352508).

Original entry on oeis.org

144, 15630, 164862, 202761, 373788, 450189, 753183, 1403961, 1779105, 2588415, 2673774, 2814229, 2850880, 3009174, 3013722, 3045870, 3091023, 3702390, 3942519, 4042950, 4432128, 4725432, 4938348, 5718942, 5907312, 6268248, 6519615, 6592752, 6791379, 7095492, 8567802
Offset: 1

Views

Author

Amiram Eldar, Mar 19 2022

Keywords

Comments

Conjecture: There are no runs of 5 consecutive Catalan-Niven numbers (checked up to 10^9).

Examples

			144 is a term since 144, 145, 146 and 147 are all divisible by the sum of the digits in their Catalan representation:
    k  A014418(k)  A014420(k)  k/A014420(k)
  ---  ----------  ----------  ------------
  144      100210           4            36
  145      100211           5            29
  146      101000           2            73
  147      101001           3            49
		

Crossrefs

Programs

  • Mathematica
    c[n_] := c[n] = CatalanNumber[n]; catNivQ[n_] := Module[{s = {}, m = n, i}, While[m > 0, i = 1; While[c[i] <= m, i++]; i--; m -= c[i]; AppendTo[s, i]]; Divisible[n, Plus @@ IntegerDigits[Total[4^(s - 1)], 4]]]; seq[count_, nConsec_] := Module[{cn = catNivQ /@ Range[nConsec], s = {}, c = 0, k = nConsec + 1}, While[c < count, If[And @@ cn, c++; AppendTo[s, k - nConsec]]; cn = Join[Rest[cn], {catNivQ[k]}]; k++]; s]; seq[5, 4]

A364219 Starts of runs of 4 consecutive integers that are Jacobsthal-Niven numbers (A364216).

Original entry on oeis.org

1, 42, 43, 2731, 11605, 13024, 14229, 25983, 39390, 45727, 46624, 47529, 60073, 96039, 111390, 131103, 132010, 133984, 134430, 140767, 148180, 148181, 148509, 174762, 174763, 187744, 197790, 237609, 247114, 266453, 275229, 287988, 312190, 330847, 354429, 370269
Offset: 1

Views

Author

Amiram Eldar, Jul 14 2023

Keywords

Crossrefs

Subsequence of A364216, A364217 and A364218.
Subsequences: A364220, A364221.

Programs

  • Mathematica
    consecJacobsthalNiven[4*10^5, 4] (* using the function from A364217 *)
  • PARI
    lista(4*10^5, 4) \\ using the function from A364217

A364382 Starts of runs of 4 consecutive integers that are greedy Jacobsthal-Niven numbers (A364379).

Original entry on oeis.org

1, 2, 3, 8, 9, 42, 43, 84, 85, 2730, 2731, 5460, 5461, 21864, 21865, 59477, 60073, 66303, 75048, 112509, 156607, 174762, 174763, 283327, 312190, 320768, 349524, 349525, 351570, 354429, 374589, 384039, 479037, 504510, 527103, 624040, 625470, 656829, 688830, 711423
Offset: 1

Views

Author

Amiram Eldar, Jul 21 2023

Keywords

Crossrefs

Subsequence of A364379, A364380 and A364381.
A364383 is a subsequence.

Programs

  • Mathematica
    consecGreedyJN[72000, 4] (* using the function consecGreedyJN from A364380 *)
  • PARI
    lista(10^5, 4) \\ using the function lista from A364380

A364126 Starts of runs of 4 consecutive integers that are Stolarsky-Niven numbers (A364123).

Original entry on oeis.org

125340, 945591, 14998632, 16160505, 19304934, 42053801, 42064137, 46049955, 57180537, 103562368, 108489885, 122495982, 135562299, 139343337, 147991452, 164002374, 271566942, 296019657, 301748706, 310980030, 314537247, 316725570, 333478935, 336959907, 349815255
Offset: 1

Views

Author

Amiram Eldar, Jul 07 2023

Keywords

Comments

Are there runs of 5 or more consecutive integers that are Stolarsky-Niven numbers?

Crossrefs

Programs

  • Mathematica
    seq[2, 4] (* generates the first 2 terms, using the function seq[count, nConsec] from A364124 *)
  • PARI
    lista(2, 4) \\ generates the first 2 terms, using the function lista(count, nConsec) from A364124

A364009 Starts of runs of 4 consecutive integers that are Wythoff-Niven numbers (A364006).

Original entry on oeis.org

374, 978, 17708, 832037, 1631097, 4821894, 5572377, 13376142, 14808759, 14930343, 35406720, 36534357, 38208519, 38748444, 38890509, 39088166, 65375232, 70046899, 79988116, 81224637, 82071105, 82898100, 94109430, 94875417, 95070492, 98014500, 100350522, 101651787, 102190437
Offset: 1

Views

Author

Amiram Eldar, Jul 01 2023

Keywords

Comments

Are there runs of 5 or more consecutive integers that are Wythoff-Niven numbers?

Crossrefs

Programs

  • Mathematica
    seq[3, 4] (* generates the first 3 terms using the function seq[count, nConsec] from A364007 *)
Showing 1-10 of 10 results.