A333537 -id:A333537 - cp's OEIS frontend

A333538 Indices of records in A333537.

1, 5, 21, 91, 355, 456, 666, 2927, 4946, 6064, 6188, 6192, 13858, 14884, 39592, 54429, 77603, 87566, 210905, 245770, 422097, 585876, 908602, 976209, 1240768, 1340675, 1573890, 2589172, 4740893, 5168099, 8525972, 8646462, 10478354, 12636785, 17943798, 19524935

Offset: 1

N. J. A. Sloane, Apr 12 2020

nonn

The first few primes that are not record values of A333537 are 2, 11, 53, 59, 71, 73, 89, 97, 103, 107 (see A333541, A333542). - Robert Israel, Apr 12 2020

a(72) > 5*10^9. - David A. Corneth, Apr 14 2020

David A. Corneth, Table of n, a(n) for n = 1..71 (first 36 terms from Robert Israel)
J. S. Myers, R. Schroeppel, S. R. Shannon, N. J. A. Sloane, and P. Zimmermann, Three Cousins of Recaman's Sequence, arXiv:2004:14000 [math.NT], April 2020.

Cf. A061836, A332558, A332559, A333537, A333541, A333542.

f:= proc(n) local k, p;
  p:= n;
  for k from 1 do
    p:= p*(n+k);
    if (p/(n+k+1))::integer then return n+k+1 fi
  od
end proc:
R:= 1: g:= 3: count:= 1:
for n from 2 while count < 20 do
  x:= max(numtheory:-factorset(f(n)));
  if x > g then count:= count+1; g:= x; R:= R, n;  fi
od:
R; # Robert Israel, Apr 12 2020

f[n_] := Module[{k, p = n}, For[k = 1, True, k++, p *= (n+k); If[Divisible[ p, n + k + 1], Return[FactorInteger[n + k + 1][[-1, 1]]]]]];
R = {1}; g = 3; count = 1;
For[n = 2, count < 20, n++, x = f[n]; If[x > g, count++; g = x; AppendTo[R, n]]];
R (* Jean-François Alcover, Aug 17 2020, after Robert Israel *)

a(13)-a(20) from Robert Israel, Apr 12 2020

More terms from Jinyuan Wang, Apr 12 2020

A333541 Records in A333537.

Original entry on oeis.org

3, 5, 7, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 61, 67, 79, 83, 101, 109, 113, 137, 139, 149, 151, 157, 167, 199, 211, 227, 239, 257, 269, 277, 283, 307, 313, 317, 353, 373, 379, 389, 397, 409, 433, 439, 499, 503, 569, 571, 593, 607, 617, 631, 701, 709, 727, 743, 757, 769, 773

Offset: 1

N. J. A. Sloane, Apr 20 2020, using data from Robert Israel's comment in A333538

nonn

For the primes that are not records, see A333542.

			For n = 91 as A332558(91) = 12 we have (91 + A332558(91) + 1) = (91 + 12 + 1) | (91 * 92 * ... * (91 + 12)) = (91 * 92 * ... * (91 + A332558(91))). The largest prime factor of 91 + 12 + 1 = 104 is 13. For no m < 91 the largest prime factor of m + A332558(m) + 1 = A332559(m) is at least 13 so 13 is a new record in A333537. - _David A. Corneth_, Apr 21 2020

David A. Corneth, Table of n, a(n) for n = 1..71
J. S. Myers, R. Schroeppel, S. R. Shannon, N. J. A. Sloane, and P. Zimmermann, Three Cousins of Recaman's Sequence, arXiv:2004:14000 [math.NT], April 2020.

Cf. A332558, A333537, A333538, A333542.

More terms from David A. Corneth, Apr 21 2020

A332558 a(n) is the smallest k such that n(n+1)(n+2)...(n+k) is divisible by n+k+1.

Original entry on oeis.org

4, 3, 2, 3, 4, 5, 4, 3, 5, 4, 6, 5, 6, 5, 4, 7, 6, 5, 4, 3, 6, 7, 6, 5, 4, 8, 7, 6, 6, 5, 8, 7, 6, 5, 4, 8, 7, 6, 5, 7, 6, 5, 10, 9, 8, 9, 8, 7, 6, 9, 8, 7, 6, 5, 4, 6, 12, 11, 10, 9, 8, 7, 6, 7, 6, 5, 12, 11, 10, 9, 8, 7, 6, 5, 8, 7, 6, 11, 10, 9, 8, 7, 6, 5

Offset: 1

Scott R. Shannon and N. J. A. Sloane, Feb 24 2020

This is a multiplicative analog of A332542.

a(n) always exists because one can take k to be 2^m - 1 for m large.

Robert Israel, Table of n, a(n) for n = 1..10000
David A. Corneth, PARI program
J. S. Myers, R. Schroeppel, S. R. Shannon, N. J. A. Sloane, and P. Zimmermann, Three Cousins of Recaman's Sequence, arXiv:2004.14000 [math.NT], April 2020.

Cf. A061836 (k+1), A332559 (n+k+1), A332560 (the final product), A332561 (the quotient).
For records, see A333532 and A333533 (and A333537), which give the records in the essentially identical sequence A061836.
Additive version: A332542, A332543, A332544, A081123.
"Concatenate in base 10" version: A332580, A332584, A332585.

f:= proc(n) local k,p;
  p:= n;
  for k from 1 do
    p:= p*(n+k);
    if (p/(n+k+1))::integer then return k fi
  od
end proc:
map(f, [$1..100]); # Robert Israel, Feb 25 2020

a[n_] := Module[{k, p = n}, For[k = 1, True, k++, p *= (n+k); If[Divisible[p, n+k+1], Return[k]]]];
Array[a, 100] (* Jean-François Alcover, Jun 04 2020, after Maple *)

a(n) = {my(r=n*(n+1)); for(k=2, oo, r=r*(n+k); if(r%(n+k+1)==0, return(k))); } \\ Jinyuan Wang, Feb 25 2020

PARI
```
\\ See Corneth link
```

def a(n):
    k, p = 1, n*(n+1)
    while p%(n+k+1): k += 1; p *= (n+k)
    return k
print([a(n) for n in range(1, 85)]) # Michael S. Branicky, Jun 06 2021

a(n) = A061836(n) - 1 for n >= 1.

a(n + 1) >= a(n) - 1. a(n + 1) = a(n) - 1 mostly. - David A. Corneth, Apr 14 2020

A061836 a(n) = smallest k>0 such that k+n divides k!.

Original entry on oeis.org

1, 5, 4, 3, 4, 5, 6, 5, 4, 6, 5, 7, 6, 7, 6, 5, 8, 7, 6, 5, 4, 7, 8, 7, 6, 5, 9, 8, 7, 7, 6, 9, 8, 7, 6, 5, 9, 8, 7, 6, 8, 7, 6, 11, 10, 9, 10, 9, 8, 7, 10, 9, 8, 7, 6, 5, 7, 13, 12, 11, 10, 9, 8, 7, 8, 7, 6, 13, 12, 11, 10, 9, 8, 7, 6, 9

Offset: 0

Robert G. Wilson v, Jun 22 2001

nonn

Comments from M. F. Hasler, Feb 20 2020 (Start)
The index at which any n > 2 appears for the last time is given by A005096(n) = n! - n.
For m>2, a(n) > m for n > A005096(m).
The integer 1 appears only once as a(0), the integer 2 is the only positive integer which never appears. (End)
It would be nice to have an estimate for the growth of the upper envelope of this sequence - what is lim sup a(n)? The answer seems to be controlled by A333537. - N. J. A. Sloane, Apr 12 2020
Paul Zimmermann suggests that perhaps a(n) is O(log(n)^2). My estimate was n^(1/3), although that seems a bit low. - N. J. A. Sloane, Apr 09 2020

Rémy Sigrist, Table of n, a(n) for n = 0..10000
J. S. Myers, R. Schroeppel, S. R. Shannon, N. J. A. Sloane, and P. Zimmermann, Three Cousins of Recaman's Sequence, arXiv:2004:14000 [math.NT], April 2020.
N. J. A. Sloane, Table of n, a(n) for n = 0..100000

Cf. A332584 for a "concatenation in base 10" variant.
See also A005096, A332558 (essentially identical to this one).
For records, see A333532 and A333533 (and A333537).

f[n_] := (k = 1; While[ !IntegerQ[ k! / (k + n) ], k++ ]; k); Table[ f[n], {n, 0, 75} ]

a(n) = my (f=1); for (k=1, oo, if ((f*=k)%(n+k)==0, return (k))) \\ Rémy Sigrist, Feb 17 2020

"k>0" added to definition at the suggestion of Chai Wah Wu, Apr 09 2020. - N. J. A. Sloane, Apr 22 2020

A333542 The primes missing from A333541.

Original entry on oeis.org

2, 11, 53, 59, 71, 73, 89, 97, 103, 107, 127, 131, 163, 173, 179, 181, 191, 193, 197, 223, 229, 233, 241, 251, 263, 271, 281, 293, 311, 331, 337, 347, 349, 359, 367, 383, 401, 419, 421, 431, 443, 449, 457, 461, 463, 467, 479, 487, 491, 509, 521, 523, 541, 547, 557, 563

Offset: 1

N. J. A. Sloane, Apr 20 2020

nonn

These are the primes that are not record high values in A333537.

			We have A333541(k) = 7 for some k and the term after that A333541(k + 1) = 13. As 11 is a prime between 7 and 13, 11 is in the sequence. - _David A. Corneth_, Apr 21 2020

David A. Corneth, Table of n, a(n) for n = 1..100
J. S. Myers, R. Schroeppel, S. R. Shannon, N. J. A. Sloane, and P. Zimmermann, Three Cousins of Recaman's Sequence, arXiv:2004:14000 [math.NT], April 2020.

Cf. A332558, A333537, A333538, A333541.

More terms from David A. Corneth, Apr 21 2020

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A333538 Indices of records in A333537.

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A333541 Records in A333537.

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A332558 a(n) is the smallest k such that n*(n+1)*(n+2)*...*(n+k) is divisible by n+k+1.

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A061836 a(n) = smallest k>0 such that k+n divides k!.

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A333542 The primes missing from A333541.

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A332558 a(n) is the smallest k such that n(n+1)(n+2)...(n+k) is divisible by n+k+1.