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 1-8 of 8 results.

A322316 Lexicographically earliest such sequence a that a(i) = a(j) => A122841(i) = A122841(j) and A244417(i) = A244417(j), for all i, j.

Original entry on oeis.org

1, 2, 2, 3, 1, 4, 1, 5, 3, 2, 1, 6, 1, 2, 2, 7, 1, 6, 1, 3, 2, 2, 1, 8, 1, 2, 5, 3, 1, 4, 1, 9, 2, 2, 1, 10, 1, 2, 2, 5, 1, 4, 1, 3, 3, 2, 1, 11, 1, 2, 2, 3, 1, 8, 1, 5, 2, 2, 1, 6, 1, 2, 3, 12, 1, 4, 1, 3, 2, 2, 1, 13, 1, 2, 2, 3, 1, 4, 1, 7, 7, 2, 1, 6, 1, 2, 2, 5, 1, 6, 1, 3, 2, 2, 1, 14, 1, 2, 3, 3, 1, 4, 1, 5, 2
Offset: 1

Views

Author

Antti Karttunen, Dec 04 2018

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A122841(n), A244417(n)].
Essentially also the restricted growth sequence transform of the unordered pair {A007814(n), A007949(n)}.
For all i, j: a(i) = a(j) => A072078(i) = A072078(j).

Crossrefs

Cf. A007814, A007949, A122841, A244417, A322026, A322317 (ordinal transform).

Programs

  • PARI
    up_to = 65537;
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    A007814(n) = valuation(n,2);
    A007949(n) = valuation(n,3);
    A122841(n) = min(A007814(n), A007949(n));
    A244417(n) = max(valuation(n,2), valuation(n,3));
    v322316 = rgs_transform(vector(up_to, n, [A122841(n), A244417(n)]));
    \\ The following is equivalent:
    \\ v322316 = rgs_transform(vector(up_to, n, Set([A007814(n), A007949(n)])));
    A322316(n) = v322316[n];

A054707 Number of powers of 6 modulo n.

Original entry on oeis.org

1, 2, 2, 3, 1, 2, 2, 4, 3, 2, 10, 3, 12, 3, 2, 5, 16, 3, 9, 3, 3, 11, 11, 4, 5, 13, 4, 4, 14, 2, 6, 6, 11, 17, 2, 3, 4, 10, 13, 4, 40, 3, 3, 12, 3, 12, 23, 5, 14, 6, 17, 14, 26, 4, 10, 5, 10, 15, 58, 3, 60, 7, 4, 7, 12, 11, 33, 18, 12, 3, 35, 4, 36, 5, 6, 11, 10, 13, 78, 5, 5, 41, 82, 4, 16
Offset: 1

Views

Author

Henry Bottomley, Apr 20 2000

Keywords

Crossrefs

Cf. A054703 (base 2), A054704 (3), A054705 (4), A054706 (5), A054708 (7), A054709 (8), A054717 (9), A054710 (10), A351524 (11), A054712 (12), A054713 (13), A054714 (14), A054715 (15), A054716 (16).

Programs

  • Mathematica
    a[n_] := Module[{e = IntegerExponent[n, {2, 3}]}, Max[e] + MultiplicativeOrder[6, n/Times @@ ({2, 3}^e)]]; Array[a, 100] (* Amiram Eldar, Aug 25 2024 *)

Formula

a(n) = A007737(n) + A244417(n). - Amiram Eldar, Aug 25 2024

A322026 Lexicographically earliest infinite sequence such that a(i) = a(j) => A007814(i) = A007814(j) and A007949(i) = A007949(j), for all i, j, where A007814 and A007949 give the 2- and 3-adic valuations of n.

Original entry on oeis.org

1, 2, 3, 4, 1, 5, 1, 6, 7, 2, 1, 8, 1, 2, 3, 9, 1, 10, 1, 4, 3, 2, 1, 11, 1, 2, 12, 4, 1, 5, 1, 13, 3, 2, 1, 14, 1, 2, 3, 6, 1, 5, 1, 4, 7, 2, 1, 15, 1, 2, 3, 4, 1, 16, 1, 6, 3, 2, 1, 8, 1, 2, 7, 17, 1, 5, 1, 4, 3, 2, 1, 18, 1, 2, 3, 4, 1, 5, 1, 9, 19, 2, 1, 8, 1, 2, 3, 6, 1, 10, 1, 4, 3, 2, 1, 20, 1, 2, 7, 4, 1, 5, 1, 6, 3
Offset: 1

Views

Author

Antti Karttunen, Dec 03 2018

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A007814(n), A007949(n)].
For all i, j:
A305900(i) = A305900(j) => a(i) = a(j),
a(i) = a(j) => A122841(i) = A122841(j),
a(i) = a(j) => A244417(i) = A244417(j),
a(i) = a(j) => A322316(i) = A322316(j) => A072078(i) = A072078(j).
If and only if a(k) > a(i) for all k > i then k is in A003586, - David A. Corneth, Dec 03 2018
That is, A003586 gives the positions of records (1, 2, 3, 4, 5, ...) in this sequence.
Sequence A126760 (without its initial zero) and this sequence are ordinal transforms of each other.

Crossrefs

Cf. A003586 (positions of records, the first occurrence of n), A007814, A007949, A065331, A071521, A072078, A087465, A122841, A126760 (ordinal transform), A322316, A323883, A323884.
Cf. also A247714 and A255975.

Programs

  • PARI
    up_to = 65537;
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    A007814(n) = valuation(n,2);
    A007949(n) = valuation(n,3);
    v322026 = rgs_transform(vector(up_to, n, [A007814(n), A007949(n)]));
    A322026(n) = v322026[n];
    
  • PARI
    A065331(n) = (3^valuation(n, 3)<A065331
    A071521(n) = { my(t=1/3); sum(k=0, logint(n, 3), t*=3; logint(n\t, 2)+1); }; \\ From A071521.
    A322026(n) = A071521(A065331(n)); \\ Antti Karttunen, Sep 08 2024

Formula

For s = A003586(n), a(s) = n = a((6k+1)*s) = a((6k-1)*s), where s is the n-th 3-smooth number and k > 0. - David A. Corneth, Dec 03 2018
A065331(n) = A003586(a(n)). - David A. Corneth, Dec 04 2018
From Antti Karttunen, Sep 08 2024: (Start)
a(n) = Sum{k=1..n} [A126760(k)==A126760(n)], where [ ] is the Iverson bracket.
a(n) = A071521(A065331(n)). [Found by Sequence Machine and also by LODA miner]
a(n) = A323884(25*n). [Conjectured by Sequence Machine]
(End)

A375538 Numerator of the asymptotic mean over the positive integers of the maximum exponent in the prime factorization of the largest prime(n)-smooth divisor function.

Original entry on oeis.org

1, 13, 51227, 926908275845, 548123689541583443758024333411, 629375533747930240763697631488051776709110194920714685268467462860005271344878614119
Offset: 1

Views

Author

Amiram Eldar, Aug 19 2024

Keywords

Comments

The numbers of digits of the terms are 1, 2, 5, 12, 30, 84, 215, 537, 1237, 2930, 6775, 15484, 35185, ... .

Examples

			Fractions begins: 1, 13/10, 51227/36540, 926908275845/636617813832, 548123689541583443758024333411/369693143251781030056182487680, ...
For n = 1, prime(1) = 2, the "2-smooth numbers" are the powers of 2 (A000079), and the sequence that gives the exponent of the largest power of 2 that divides n is A007814, whose asymptotic mean is 1.
For n = 2, prime(2) = 3, the 3-smooth numbers are in A003586, and the sequence that gives the maximum exponent in the prime factorization of the largest 3-smooth divisor of n is A244417, whose asymptotic mean is 13/10.
		

Crossrefs

Cf. A033150, A375537, A375539 (denominators).
Cf. A375538 (numerators).

Programs

  • Mathematica
    d[k_, n_] := Product[1 - 1/Prime[i]^k, {i, 1, n}]; f[n_] := Sum[k * (d[k+1, n] - d[k, n]), {k, 1, Infinity}]; Numerator[Array[f, 6]]

Formula

Let f(n) = a(n)/A375539(n). Then:
f(n) = lim_{m->oo} (1/m) * Sum_{i=1..m} A375537(n, i).
f(n) = Sum_{k>=1} k * (d(k+1, prime(n)) - d(k, prime(n))), where d(k, p) = Product_{q prime <= p} (1 - 1/q^k).
Limit_{n->oo} f(n) = A033150.

A322317 Ordinal transform of A322316.

Original entry on oeis.org

1, 1, 2, 1, 2, 1, 3, 1, 2, 3, 4, 1, 5, 4, 5, 1, 6, 2, 7, 3, 6, 7, 8, 1, 9, 8, 2, 4, 10, 2, 11, 1, 9, 10, 12, 1, 13, 11, 12, 3, 14, 3, 15, 5, 6, 13, 16, 1, 17, 14, 15, 7, 18, 2, 19, 4, 16, 17, 20, 3, 21, 18, 8, 1, 22, 4, 23, 9, 19, 20, 24, 1, 25, 21, 22, 10, 26, 5, 27, 2, 3, 23, 28, 4, 29, 24, 25, 5, 30, 5, 31, 11, 26, 27, 32, 1
Offset: 1

Views

Author

Antti Karttunen, Dec 04 2018

Keywords

Crossrefs

Programs

  • PARI
    up_to = 65537;
    ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om,invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om,invec[i],(1+pt))); outvec; };
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    A007814(n) = valuation(n,2);
    A007949(n) = valuation(n,3);
    A122841(n) = min(A007814(n), A007949(n));
    A244417(n) = max(valuation(n,2), valuation(n,3));
    v322316 = rgs_transform(vector(up_to, n, [A122841(n), A244417(n)]));
    v322317 = ordinal_transform(v322316);
    A322317(n) = v322317[n];

A375536 The maximum exponent in the prime factorization of the largest 5-smooth divisor of n.

Original entry on oeis.org

0, 1, 1, 2, 1, 1, 0, 3, 2, 1, 0, 2, 0, 1, 1, 4, 0, 2, 0, 2, 1, 1, 0, 3, 2, 1, 3, 2, 0, 1, 0, 5, 1, 1, 1, 2, 0, 1, 1, 3, 0, 1, 0, 2, 2, 1, 0, 4, 0, 2, 1, 2, 0, 3, 1, 3, 1, 1, 0, 2, 0, 1, 2, 6, 1, 1, 0, 2, 1, 1, 0, 3, 0, 1, 2, 2, 0, 1, 0, 4, 4, 1, 0, 2, 1, 1, 1, 3, 0, 2, 0, 2, 1, 1, 1, 5, 0, 1, 2, 2, 0, 1, 0, 3, 1
Offset: 1

Views

Author

Amiram Eldar, Aug 19 2024

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := Max[IntegerExponent[n, {2, 3, 5}]]; Array[a, 100]
  • PARI
    a(n) = max(max(valuation(n, 2), valuation(n, 3)), valuation(n, 5));

Formula

a(n) = A051903(A355582(n)).
a(n) = max(A007814(n), A007949(n), A112765(n)).
a(n) = 0 if and only if n is a 7-rough number (A007775).
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = A375538(3)/A375539(3) = 51227/36540 = 1.401943076...

A375537 Square array A(n, k) (n, k >= 1) read by antidiagonals in ascending order: A(n, k) = Max_{i = 1..n} v_prime(i)(k), where v_p(k) is the p-adic valuation of k.

Original entry on oeis.org

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

Views

Author

Amiram Eldar, Aug 19 2024

Keywords

Comments

For a given n, A(n, k) is the sequence that gives the maximum exponent in the prime factorization of the largest prime(n)-smooth divisor of k.

Examples

			Array begins:
   n | n-th row
  ---+-----------------------------
   1 | 0, 1, 0, 2, 0, 1, 0, 3, 0, 1
   2 | 0, 1, 1, 2, 0, 1, 0, 3, 2, 1
   3 | 0, 1, 1, 2, 1, 1, 0, 3, 2, 1
   4 | 0, 1, 1, 2, 1, 1, 1, 3, 2, 1
   5 | 0, 1, 1, 2, 1, 1, 1, 3, 2, 1
   6 | 0, 1, 1, 2, 1, 1, 1, 3, 2, 1
   7 | 0, 1, 1, 2, 1, 1, 1, 3, 2, 1
   8 | 0, 1, 1, 2, 1, 1, 1, 3, 2, 1
   9 | 0, 1, 1, 2, 1, 1, 1, 3, 2, 1
  10 | 0, 1, 1, 2, 1, 1, 1, 3, 2, 1
		

Crossrefs

Programs

  • Mathematica
    A[n_, k_] := Max[IntegerExponent[k, Prime[Range[n]]]]; Table[A[n - k + 1, k], {n, 1, 14}, {k, 1 n}] // Flatten
  • PARI
    A(n, k) = vecmax(apply(x -> valuation(k, x), primes(n)));

Formula

A(n, k) = Max_{i=1..n} A249344(i, k).
A(n, k) = A051903(k) for n >= A000720(A006530(k)).
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{i=1..m} A(n, i) = A375538(n)/A375539(n).

A244416 6-adic value of 1/n for n >= 1.

Original entry on oeis.org

1, 6, 6, 36, 1, 6, 1, 216, 36, 6, 1, 36, 1, 6, 6, 1296, 1, 36, 1, 36, 6, 6, 1, 216, 1, 6, 216, 36, 1, 6, 1, 7776, 6, 6, 1, 36, 1, 6, 6, 216, 1, 6, 1, 36, 36, 6, 1, 1296, 1, 6, 6, 36, 1, 216, 1, 216, 6, 6, 1, 36, 1, 6, 36, 46656, 1, 6, 1, 36, 6, 6, 1, 216, 1, 6, 6, 36, 1, 6, 1, 1296, 1296, 6, 1, 36, 1, 6
Offset: 1

Views

Author

Wolfdieter Lang, Jun 30 2014

Keywords

Comments

For the definition of 'g-adic value of x', called |x|_g with g an integer >= 2, see the Mahler reference, p. 7. Sometimes also called g-adic absolute value of x. If g is not a prime then this is called a non-archimeden pseudo-valuation. See Mahler, p. 10.

Examples

			a(6) = 6^max(1,1) = 6^1 = 6. a(12) = 6^max(2,1) = 6^2 = 36,
a(18) = 6^max(1,2) = 36, a(24) = 6^max(3,1) = 6^3 = 216, ...
a(2) = 6^1 = 6, a(8) = 6^3 = 216, a(14) = 6^1 = 6, ...
a(3) = 6^1 = 6, a(9) = 6^2 = 36, a(15) = 6^1 = 6, ...
a(4) = 6^2 = 36, a(10) = 6^1 = 6, a(16) = 6^4 = 1296, ...
		

References

  • Kurt Mahler, p-adic numbers and their functions, second ed., Cambridge University Press, 1981.

Crossrefs

Cf. A244417, A006519 (g=2), A038500 (g=3), A240226 (g=4), A060904 (g=5).

Programs

  • Mathematica
    a[n_] := 6^Max[IntegerExponent[n, {2, 3}]]; Array[a, 100] (* Amiram Eldar, Aug 19 2024 *)
  • PARI
    a(n) = 6^max(valuation(n, 2), valuation(n, 3)); \\ Amiram Eldar, Aug 19 2024

Formula

a(n) = 1 if n == 1 or 5 (mod 6). a(n) = 6^max(A007814(n), A007949(n)) if n == 0 (mod 6), a(n) = 6^A007814(n) if n == 2 or 4 (mod 6), a(n) = 6^A007949(n) if n == 3 (mod 6). The exponents, called f(1/n) in the Mahler reference, are given in A244417(n).
a(n) = 6^A244417(n). - Amiram Eldar, Aug 19 2024
Showing 1-8 of 8 results.