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 1-3 of 3 results.

A339550 Numbers k such that A339549(k) = A339549(k+1).

Original entry on oeis.org

1, 9, 85, 697, 1285, 2605, 4573, 5845, 6001, 6241, 6613, 7141, 7453, 8005, 10897, 12453, 13141, 15445, 19789, 20345, 21445, 21913, 22873, 25957, 36565, 36601, 39597, 44761, 46405, 53677, 56137, 56593, 61013, 63445, 70094, 72913, 76977, 80913, 82405, 87085, 87601
Offset: 1

Views

Author

Amiram Eldar, Dec 08 2020

Keywords

Comments

Analogous to A338452 as A339549 is analogous to A093653.

Examples

			9 is a term since A339549(9) = A339549(10) = 4.

Links

Crossrefs

Cf. A000120, A093653, A338452, A339549.

Programs

  • Mathematica
    f[n_] := Times @@ (DigitCount[#, 2, 1] & /@ Divisors[n]); Select[Range[10000], f[#] == f[# + 1] &]

A339552 Numbers k such that the product of the binary weights of the divisors of k (A339549) sets a new record.

Original entry on oeis.org

1, 3, 6, 12, 14, 15, 21, 28, 30, 42, 60, 84, 90, 120, 168, 180, 210, 252, 360, 420, 540, 630, 840, 1080, 1260, 2520, 3780, 5040, 6300, 7560, 10080, 12600, 13860, 15120, 21420, 22680, 25200, 27720, 32760, 37800, 41580, 42840, 49140, 55440, 65520, 75600, 83160
Offset: 1

Views

Author

Amiram Eldar, Dec 08 2020

Keywords

Comments

Analogous to A093687 as A339549 is analogous to A093653.
The corresponding record values of A339549 are 1, 2, 4, 8, 9, 16, 18, 27, 256, 324, ... (see the link for more values).

Links

Crossrefs

Cf. A000120, A093653, A093687, A339549.

Programs

  • Mathematica
    f[n_] := Times @@ (DigitCount[#, 2, 1] & /@ Divisors[n]); c=0; fm = 0; s = {}; Do[f1 = f[n]; If[f1 > fm, fm = f1; AppendTo[s, n]], {n, 1, 10000}]; s

A339551 Starts of runs of 3 consecutive numbers with the same product of the binary weights of their divisors (A339549).

Original entry on oeis.org

513059433, 3007912105, 4791685641, 11555664153, 44615854297, 111890605585, 121111724905, 163901238153
Offset: 1

Views

Author

Amiram Eldar, Dec 08 2020

Keywords

Comments

Analogous to A338453 as A339549 is analogous to A093653.

Examples

			513059433 is a term since A339549(513059433) = A339549(513059434) = A339549(513059435) = 1166400.

Crossrefs

Cf. A000120, A093653, A338453, A339549.
Subsequence of A339550.

Programs

  • Mathematica
    f[n_] := Times @@ (DigitCount[#, 2, 1] & /@ Divisors[n]); s = {}; m = 3; fs = f /@ Range[m]; Do[If[Equal @@  fs, AppendTo[s, n - m]]; fs = Rest @ AppendTo[fs, f[n]], {n, m + 1, 5*10^9}]; s
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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