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 1-6 of 6 results.

A328591 Even bisection of A328590: a(n) = A328578(2n) - A257993(2n).

Original entry on oeis.org

1, 2, 0, 2, 3, -1, 3, 2, 0, 4, 4, -1, 4, 5, -2, 2, 1, 0, 3, 4, -1, 4, 4, 0, 5, 5, -1, 5, 3, -2, 3, 2, 0, 4, 4, -1, 5, 5, 0, 5, 6, -1, 4, 6, -2, 4, 5, 0, 5, 5, -1, 5, 6, 0, 6, 3, -1, 7, 7, -2, 1, 5, 0, 6, 6, -1, 6, 5, 0, 7, 7, -1, 7, 8, -2, 2, 1, 0, 6, 7, -1, 7, 3, 0, 7, 5, -1, 3, 8, -2, 6, 2, 0, 7, 7, -1, 7, 8, 0, 8, 8, -1, 8, 9, -1
Offset: 1

Views

Author

Antti Karttunen, Oct 21 2019

Keywords

Crossrefs

Programs

Formula

a(n) = A328590(2n) = A328578(2n) - A257993(2n).

A328578 Index of the least prime not dividing A276086(A276086(n)): a(n) = A257993(A276087(n)).

Original entry on oeis.org

2, 1, 3, 1, 4, 1, 3, 1, 4, 1, 5, 1, 2, 1, 5, 1, 4, 1, 3, 1, 6, 1, 6, 1, 2, 1, 6, 1, 7, 1, 2, 1, 4, 1, 3, 1, 3, 1, 5, 1, 6, 1, 2, 1, 6, 1, 6, 1, 3, 1, 7, 1, 7, 1, 2, 1, 7, 1, 5, 1, 2, 1, 5, 1, 4, 1, 3, 1, 6, 1, 6, 1, 2, 1, 7, 1, 7, 1, 3, 1, 7, 1, 8, 1, 2, 1, 6, 1, 8, 1, 2, 1, 6, 1, 7, 1, 3, 1, 7, 1, 7, 1, 2, 1, 7, 1
Offset: 0

Views

Author

Antti Karttunen, Oct 20 2019

Keywords

Comments

Index of the least significant zero digit in the primorial base expansion of A276086(n), when the rightmost digit is in the position 1.
The scatter plot shows both regular looking as well as more chaotic regions. This can be more clearly seen in related A328579. See also A328839.

Crossrefs

Cf. A328585 (where equal with A257993), A328587 (less than), A328588 (greater than).
Cf. A328761 (the first occurrence of each n).
Cf. also array A328631 and its rows A005408, A328632, A328633, A328634, A328635, A328636 (positions of terms 1 .. 6 in this sequence).

Programs

Formula

a(n) = A328570(A276086(n)) = A257993(A276087(n)) = A055396(A328403(n)).
a(n) = A000720(A328579(n)).
a(n) = A257993(n) + A328590(n).
a(n) = A055396(A328763(n)).
For all n >= 0, a(A328761(n)) = n.

A328585 Numbers n for which A257993(n) is equal to A257993(A276086(A276086(n))), where A276086 converts the primorial base expansion of n into its prime product form, and A257993 returns the index of the least prime not present in its argument.

Original entry on oeis.org

1, 3, 5, 6, 7, 9, 11, 13, 15, 17, 18, 19, 21, 23, 25, 27, 29, 31, 33, 35, 36, 37, 39, 41, 43, 45, 47, 48, 49, 51, 53, 55, 57, 59, 61, 63, 65, 66, 67, 69, 71, 73, 75, 77, 78, 79, 81, 83, 85, 87, 89, 91, 93, 95, 96, 97, 99, 101, 103, 105, 107, 108, 109, 111, 113, 115, 117, 119, 121, 123, 125, 126, 127, 129, 131, 133, 135, 137, 138, 139
Offset: 1

Views

Author

Antti Karttunen, Oct 21 2019

Keywords

Comments

Numbers n for which A257993(n) is equal to A328578(n).
All odd numbers are included, as A257993(2n+1) = A328578(2n+1) = 1 for all n >= 0.

Crossrefs

Union of A005408 (odd numbers) and A328586 (even terms).
Positions of zeros in A328590.
Cf. also A328316, A328317.

Programs

A328587 Numbers n for which A257993(A276086(A276086(n))) is less than A257993(n), where A276086 converts the primorial base expansion of n into its prime product form, and A257993 returns the index of the least prime not present in its argument.

Original entry on oeis.org

12, 24, 30, 42, 54, 60, 72, 84, 90, 102, 114, 120, 132, 144, 150, 162, 174, 180, 192, 204, 210, 216, 228, 246, 258, 276, 288, 306, 318, 336, 348, 366, 378, 396, 408, 420, 432, 444, 450, 462, 474, 480, 492, 504, 510, 522, 534, 540, 552, 564, 570, 582, 594, 600, 612, 624, 636, 648, 666, 678, 696, 708, 726, 738, 756, 768, 786, 798, 816
Offset: 1

Views

Author

Antti Karttunen, Oct 21 2019

Keywords

Comments

Numbers n for which A328578(n) is less than A257993(n).
All terms are multiples of 6. The final digit {0, 2, 4, 6, 8} of the decimal representation seems to be quite evenly distributed.
Other multiples of six are in A328586 and A328589.
210 is the first term not present in A328632.

Crossrefs

Union of A328632 \ {0} and A328762.
Positions of negative terms in A328590.

Programs

A328588 Numbers n for which A257993(A276086(A276086(n))) is larger than A257993(n), where A276086 converts the primorial base expansion of n into its prime product form, and A257993 returns the index of the least prime not present in its argument.

Original entry on oeis.org

2, 4, 8, 10, 14, 16, 20, 22, 26, 28, 32, 34, 38, 40, 44, 46, 50, 52, 56, 58, 62, 64, 68, 70, 74, 76, 80, 82, 86, 88, 92, 94, 98, 100, 104, 106, 110, 112, 116, 118, 122, 124, 128, 130, 134, 136, 140, 142, 146, 148, 152, 154, 158, 160, 164, 166, 170, 172, 176, 178, 182, 184, 188, 190, 194, 196, 200, 202, 206, 208, 212, 214, 218, 220, 224, 226, 230, 232, 236, 238, 240, 242
Offset: 1

Views

Author

Antti Karttunen, Oct 21 2019

Keywords

Comments

Numbers n for which A328578(n) > A257993(n).
A047235 (numbers that are congruent to {2, 4} mod 6, thus even numbers that are not multiples of 3, with A257993(n) = 1) is a subsequence, because in primorial base (A049345) such numbers end with digits "10" or "20". A276086 will convert such a number to a number of the form p_k^e_k * ... * 7^b * 5^a * 3^{1,2} * 2^0 (an odd multiple of three, thus of the form 6k+3) which in primorial base will end with digits "11", thus on the second iteration A276086 will convert that to a number of the form p_k^e_k * ... * 7^b * 5^a * 3^1 * 2^1, with the least missing prime having an index (A257993) at least 3, which is larger than the original 1. Thus all terms of A047235 are included in this sequence.

Crossrefs

Union of A047235 (terms of the form 6k+2 and 6k+4) and A328589 (gives the terms that are multiples of 6).
Positions of positive terms in A328590.
Differs from A047235 for the first time at n=81, with a(81) = 240, a term not present in A047235.

Programs

A328589 Numbers n that are multiples of 6 and for which A257993(A276086(A276086(n))) is larger than A257993(n), where A276086 converts the primorial base expansion of n into its prime product form, and A257993 returns the index of the least prime not present in its argument.

Original entry on oeis.org

240, 270, 300, 330, 360, 390, 630, 660, 690, 720, 750, 780, 810, 1050, 1080, 1110, 1140, 1170, 1200, 1230, 1500, 1530, 1560, 1590, 1620, 1650, 1890, 1920, 1950, 1980, 2010, 2040, 2070, 2550, 2580, 2610, 2640, 2670, 2700, 2940, 2970, 3000, 3030, 3060, 3090, 3120, 3360, 3390, 3420, 3450, 3480, 3510, 3540, 3810, 3840, 3870, 3900, 3930, 3960, 4200
Offset: 1

Views

Author

Antti Karttunen, Oct 21 2019

Keywords

Comments

Multiples of six such that the least nondivisor prime of the original n is less than the least nondivisor prime of the number obtained after two iterations of A276086 is.
All terms are multiples of 5 (and thus of 30), because when applied to any number which is a multiple of 6, but not of 5 (and thus not a multiple of 30, so the primorial expansion ends with "x00", where x <> 0, and A257993(n) = 3), A276086 will yield a number of the form 30k+5 or 30k+25 (A084967) whose primorial expansion ends either as "...021" or as "...401" (with the least significant zero either in position 2 or 3), thus then A328578(n) = A257993(A276086(A276086(n))) is definitely not larger than 3, while A257993(6k) >= 3 for all k >= 1.

Crossrefs

Subsequence of A328588.
Other multiples of 6 are either in A328586 or in A328587.

Programs

Showing 1-6 of 6 results.