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 23 results. Next

A140258 Minimal multiples from A016089 of primes from A129729.

Original entry on oeis.org

2, 6, 1926, 2471058, 38259378, 41218326, 600917778, 114130755846, 600929334, 28312987734, 342397209654, 722113254, 15559317470256498, 84332966140854, 20543988255894, 1314244621926, 600935058, 6739452314987202
Offset: 1

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Author

Max Alekseyev, May 16 2008

Keywords

Comments

A016089 lists numbers n such that n divide n-th Lucas number A000032(n) while A129729 lists all possible prime divisors of elements of A016089 in the increasing order. This sequence lists minimal multiples from A016089 of primes from A129729.

Formula

a(n) = min { A016089(m) : A129729(n)|A016089(m) }

A129729 Primes dividing numbers k such that k divides the k-th Lucas number A000032(k).

Original entry on oeis.org

2, 3, 107, 1283, 8747, 21401, 34667, 46187, 104003, 137387, 138563, 374929, 549547, 2204243, 2771281, 2808107, 11128427, 11223683, 13497443, 14880347, 21747529, 22753547, 23712683, 33697283, 44513387, 46970929, 57395627, 65898683
Offset: 1

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Author

Alexander Adamchuk, May 12 2007

Keywords

Comments

A prime p belongs to this sequence iff for some positive integer m, m*p divides A000032(m*p) or, alternatively, m*p belongs to A016089.
The minimum multiples from A016089 of listed primes are given by A140258.

Crossrefs

Extensions

Revised and extended by Max Alekseyev, May 16 2008

A338638 a(n) = L(L(n)) mod L(n), where L = Lucas numbers = A000032.

Original entry on oeis.org

1, 0, 1, 3, 1, 1, 0, 1, 1, 7, 4, 1, 199, 1, 4, 843, 1, 1, 0, 1, 29, 123, 4, 1, 3, 199, 4, 39603, 29, 1, 5778, 1, 1, 7, 4, 17622890, 12752043, 1, 4, 39603, 7881196, 1, 5778, 1, 29, 7, 4, 1, 3, 1149851, 28143689044, 7, 29, 1, 0, 312119004790, 6643838879, 7, 4, 1
Offset: 0

Views

Author

Alois P. Heinz, Nov 04 2020

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) local r, M, p; r, M, p:=
          <<1|0>, <0|1>>, <<0|1>, <1|1>>, n;
          do if irem(p, 2, 'p')=1 then r:=
            `if`(nargs=1, r.M, r.M mod args[2]) fi;
             if p=0 then break fi; M:=
            `if`(nargs=1, M.M, M.M mod args[2])
          od; (r.<<2, 1>>)[1$2]
        end:
    a:= n-> (f-> b(f$2) mod f)(b(n)):
    seq(a(n), n=0..60);
  • Mathematica
    Table[Mod[LucasL[LucasL[n]],LucasL[n]],{n,0,60}] (* Harvey P. Dale, Jul 04 2022 *)

Formula

a(n) = A005371(n) mod A000032(n).
a(n) = 0 for n in { A016089 }.

A325630 Numbers k such that A000110(k) is divisible by k.

Original entry on oeis.org

1, 2, 35, 16833, 16989, 23684
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 07 2019

Keywords

Comments

No other terms below 50000.
From Amiram Eldar, Jun 20 2024: (Start)
Numbers k such that A166226(k) = 0.
All the terms above 2 are composites since A166226(p) == 2 (mod p) for prime p. (End)
No other terms below 90000. - Michael S. Branicky, Jan 09 2025

Examples

			35 is in the sequence because A000110(35) = 35 * 8045720086273150473238297902.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[1000], Divisible[BellB[#], #] &]

A272318 Integer values of Lucas number A000032(n)/n.

Original entry on oeis.org

1, 3, 321, 3572225067, 44308057022098435739157981016569
Offset: 1

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Author

Peter M. Chema, Apr 25 2016

Keywords

Comments

The digital root of this sequence appears to be alternately 3 and 6, aside from the initial term of "1".
A subsequence of A181885. For instance, a(2)=A181885(6), a(3)=A181885(18), a(4)=A181885(54); a(5)=A181885(162); and, a(6)=A181885(486). Also 6, 18, 54, 162 and 486 are consecutive terms of the Pinot sequence A008776. Is this a coincidence?

Crossrefs

Programs

  • Mathematica
    LucasL[#]/# & /@ Range@ 1200 /. _Rational -> Nothing (* Version 10.2, or *)
    Select[Array[LucasL[#]/# &, {1200}], IntegerQ] (* Michael De Vlieger, Apr 25 2016 *)

Formula

a(n) = A000032(A016089(n))/n. - Michel Marcus, Apr 25 2016

A372898 Numbers k that divide the k-th Padovan number.

Original entry on oeis.org

1, 2, 4, 16, 25, 27, 59, 69, 101, 167, 173, 211, 223, 271, 307, 317, 347, 387, 422, 449, 463, 593, 599, 607, 634, 691, 694, 719, 809, 821, 829, 844, 853, 877, 883, 898, 926, 991, 997, 1097, 1117, 1151, 1163, 1181, 1197, 1198, 1231, 1319, 1369, 1388, 1451, 1453, 1481
Offset: 1

Views

Author

Amiram Eldar, May 16 2024

Keywords

Comments

Numbers k such that k | A000931(k).

Examples

			2 is a term since A000931(2) = 0 is divisible by 2.
27 is a term since A000931(27) = 351 = 13 * 27 is divisible by 27.
		

Crossrefs

Cf. A000931.
Similar sequences: A014847 (Catalan), A016089 (Lucas), A023172 (Fibonacci), A051177 (partition), A232570 (tribonacci), A246692 (Pell), A266969 (Motzkin).

Programs

  • Mathematica
    With[{m = 1500}, Position[LinearRecurrence[{0, 1, 1}, {0, 0, 1}, m]/Range[m], _?IntegerQ] // Flatten]
  • PARI
    lista(kmax) = {my(p1 = 0, p2 = 0, p3 = 1, p4); print1("1, 2, "); for(k = 4, kmax, p4 = p1 + p2; if(!(p4 % k), print1(k, ", ")); p1 = p2; p2 = p3; p3 = p4);}

A372899 Numbers k that divide the k-th companion Pell number.

Original entry on oeis.org

1, 2, 6, 18, 54, 66, 162, 198, 486, 594, 726, 1314, 1458, 1782, 2178, 2838, 3222, 3942, 4374, 5346, 5778, 5874, 6534, 7986, 8514, 8646, 9666, 11826, 13122, 14454, 16038, 17334, 17622, 19602, 23958, 25542, 25938, 28998, 31218, 35442, 35478, 39366, 43362, 48114
Offset: 1

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Author

Amiram Eldar, May 16 2024

Keywords

Comments

Numbers k such that k | A002203(k).

Examples

			2 is a term since A002203(2) = 6 = 2 * 3 is divisible by 2.
6 is a term since A002203(6) = 198 = 6 * 33 is divisible by 6.
		

Crossrefs

Cf. A002203.
Similar sequences: A014847 (Catalan), A016089 (Lucas), A023172 (Fibonacci), A051177 (partition), A232570 (tribonacci), A246692 (Pell), A266969 (Motzkin).

Programs

  • Mathematica
    Select[Range[50000], Divisible[LucasL[#, 2], #] &]
  • PARI
    lista(kmax) = {my(p1 = 2, p2 = 6, p3); print1("1, 2, "); for(k = 3, kmax, p3 = p1 + 2*p2; if(!(p3 % k), print1(k, ", ")); p1 = p2; p2 = p3);}

A372900 Numbers k that divide the k-th term of Narayana's cows sequence.

Original entry on oeis.org

1, 6, 12, 52, 390, 650, 663, 2077, 11479, 31671, 41158, 43508, 104894, 123682, 127370, 170819, 175075, 191516, 266247, 274378, 327159, 341638, 366903, 383847, 733985, 1236087, 1755063, 1763775, 2277964, 2364654, 3165126, 6726156, 7007823, 7221084, 10903815
Offset: 1

Views

Author

Amiram Eldar, May 16 2024

Keywords

Comments

Numbers k such that k | A000930(k).

Examples

			6 is a term since A000930(6) = 6 is divisible by 6.
12 is a term since A000930(12) = 60 = 5 * 12 is divisible by 12.
		

Crossrefs

Cf. A000930.
Similar sequences: A014847 (Catalan), A016089 (Lucas), A023172 (Fibonacci), A051177 (partition), A232570 (tribonacci), A246692 (Pell), A266969 (Motzkin).

Programs

  • Mathematica
    With[{m = 50000}, Position[LinearRecurrence[{1, 0, 1}, {1, 1, 2}, m]/Range[m], _?IntegerQ] // Flatten]
  • PARI
    lista(kmax) = {my(nc1 = 1, nc2 = 1, nc3 = 2, nc4); print1("1, "); for(k = 4, kmax, nc4 = nc1 + nc3; if(!(nc4 % k), print1(k, ", ")); nc1 = nc2; nc2 = nc3; nc3 = nc4);}

A372901 Numbers k that divide the k-th central Delannoy number.

Original entry on oeis.org

1, 3, 9, 21, 27, 81, 171, 189, 217, 243, 297, 351, 729, 903, 1547, 2187, 3591, 3661, 4131, 5499, 5967, 6019, 6561, 7533, 8001, 11997, 13203, 14217, 15309, 17181, 19683, 20601, 22113, 22599, 23529, 24297, 25659, 26163, 26319, 26487, 28441, 30051, 33021, 37179, 37791
Offset: 1

Views

Author

Amiram Eldar, May 16 2024

Keywords

Comments

Numbers k such that k | A001850(k).

Examples

			3 is a term since A001850(3) = 63 = 3 * 21 is divisible by 3.
9 is a term since A001850(9) = 1462563 = 9 * 162507 is divisible by 9.
		

Crossrefs

Cf. A001850.
Similar sequences: A014847 (Catalan), A016089 (Lucas), A023172 (Fibonacci), A051177 (partition), A232570 (tribonacci), A246692 (Pell), A266969 (Motzkin).

Programs

  • Mathematica
    Select[Range[1000], Divisible[LegendreP[#, 3], #] &]
  • PARI
    lista(kmax) = {my(cd0 = 1, cd1 = 3, cd2); print1("1, "); for(k = 2, kmax, cd2 = (3*(2*k-1)*cd1 - (k-1)*cd0)/k; if(!(cd2 % k), print1(k, ", ")); cd0 = cd1; cd1 = cd2);}

A372902 Numbers k that divide the k-th large Schröder number.

Original entry on oeis.org

1, 2, 6, 33, 42, 154, 198, 258, 270, 342, 850, 1170, 1666, 1806, 2295, 2574, 3262, 3366, 3834, 4070, 4654, 4970, 5439, 6006, 6118, 6162, 6699, 7095, 7254, 7497, 7595, 10241, 11475, 12642, 14014, 15345, 17470, 17670, 18018, 19845, 22446, 23994, 24570, 24651, 25245, 25974, 26334
Offset: 1

Views

Author

Amiram Eldar, May 16 2024

Keywords

Comments

Numbers k such that k | A006318(k).

Examples

			2 is a term since A001850(2) = 6 = 2 * 3 is divisible by 2.
6 is a term since A001850(6) = 1806 = 6 * 301 is divisible by 6.
		

Crossrefs

Cf. A006318.
Similar sequences: A014847 (Catalan), A016089 (Lucas), A023172 (Fibonacci), A051177 (partition), A232570 (tribonacci), A246692 (Pell), A266969 (Motzkin).

Programs

  • Mathematica
    seq[kmax_] := Module[{sc0 = 1, sc1 = 2, sc2, s = {1}}, Do[sc2 = ((6*k-3)*sc1 - (k-2)*sc0)/(k+1); If[Divisible[sc2, k], AppendTo[s, k]]; sc0 = sc1; sc1 = sc2, {k, 2, kmax}]; s]; seq[27000]
  • PARI
    lista(kmax) = {my(sc0 = 1, sc1 = 2, sc2); print1(1, ", "); for(k = 2, kmax, sc2 = ((6*k-3)*sc1 - (k-2)*sc0)/(k+1); if(!(sc2 % k), print1(k, ", ")); sc0 = sc1; sc1 = sc2);}
Showing 1-10 of 23 results. Next