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 1-4 of 4 results.

A278538 a(n) = index of the row where n is located in array A278505.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Nov 23 2016

Keywords

Comments

Ordinal transform of A278539 (most likely, but hinges on that also the columns of A278505 are strictly growing).

Crossrefs

Programs

Formula

If A278169(n) = 1, a(n) = A100617(n), otherwise a(n) = A278528(n).
If n = A000960(k), a(n) = k, otherwise a(n) = number of the round in which n is removed in the Flavius sieve.

A278539 a(n) = index of the column where n is located in array A278505.

Original entry on oeis.org

1, 2, 1, 3, 2, 4, 1, 5, 2, 6, 3, 7, 1, 8, 2, 9, 4, 10, 1, 11, 3, 12, 5, 13, 2, 14, 1, 15, 6, 16, 2, 17, 4, 18, 7, 19, 3, 20, 1, 21, 8, 22, 2, 23, 5, 24, 9, 25, 1, 26, 3, 27, 10, 28, 4, 29, 6, 30, 11, 31, 2, 32, 1, 33, 12, 34, 2, 35, 7, 36, 13, 37, 3, 38, 5, 39, 14, 40, 1, 41, 8, 42, 15, 43, 4, 44, 2, 45, 16, 46, 1, 47, 9, 48, 17, 49, 6, 50, 3, 51, 18, 52, 2, 53
Offset: 1

Views

Author

Antti Karttunen, Nov 23 2016

Keywords

Comments

Ordinal transform of A278538 (as the rows of A278505 are strictly growing).

Crossrefs

One more than A278529.

Programs

Formula

a(n) = 1 + A278529(n).

A278511 Square array constructed from Flavius sieve, shifted version, read by descending antidiagonals.

Original entry on oeis.org

2, 4, 3, 6, 5, 7, 8, 11, 9, 13, 10, 17, 21, 15, 19, 12, 23, 33, 37, 25, 27, 14, 29, 45, 55, 51, 31, 39, 16, 35, 57, 75, 85, 73, 43, 49, 18, 41, 69, 97, 111, 121, 99, 61, 63, 20, 47, 81, 115, 145, 159, 151, 127, 67, 79, 22, 53, 93, 135, 171, 199, 211, 193, 163, 87, 91, 24, 59, 105, 157, 205, 243, 267, 271, 247, 187, 103, 109
Offset: 1

Views

Author

Antti Karttunen, Nov 23 2016

Keywords

Comments

Note how in comparison to A278505, the even numbers on the first row have been shifted one step left, "pushing" term 1 out of the array proper. This was done to obtain a better alignment with arrays like A083221 and A255127 associated with other sieves, from which one may then induce permutations by cross-referencing. (See also A255551.)

Examples

			The top left corner of the array:
   2,  4,   6,   8,  10,  12,  14,  16,  18,  20
   3,  5,  11,  17,  23,  29,  35,  41,  47,  53
   7,  9,  21,  33,  45,  57,  69,  81,  93, 105
  13, 15,  37,  55,  75,  97, 115, 135, 157, 175
  19, 25,  51,  85, 111, 145, 171, 205, 231, 265
  27, 31,  73, 121, 159, 199, 243, 283, 327, 367
  39, 43,  99, 151, 211, 267, 319, 379, 433, 487
  49, 61, 127, 193, 271, 343, 421, 483, 559, 631
  63, 67, 163, 247, 339, 427, 519, 607, 691, 793
  79, 87, 187, 303, 403, 523, 639, 739, 853, 963
		

Crossrefs

Inverse: A278512.
Cf. A000960 (column 1, but with its initial 1 replaced by 2), A278505, A278507.
Cf. A278538 (row index of n), A278537 (column index of n).
Cf. A083221, A255127, A255551 (analogous arrays constructed from other sieves).

Programs

Formula

A(1,col) = 2*col; For row > 1, A(row,1) = A000960(row) if col = 1, otherwise, A(row,col) = A278507(row,col-1).
For all n > 1, A(A278538(n), A278537(n)) = n.

A278512 Inverse permutation to A278511.

Original entry on oeis.org

1, 2, 4, 3, 6, 5, 7, 8, 10, 12, 9, 17, 11, 23, 15, 30, 13, 38, 16, 47, 14, 57, 18, 68, 21, 80, 22, 93, 24, 107, 28, 122, 19, 138, 31, 155, 20, 173, 29, 192, 39, 212, 36, 233, 25, 255, 48, 278, 37, 302, 27, 327, 58, 353, 26, 380, 32, 408, 69, 437, 45, 467, 46, 498, 81, 530, 55, 563, 40, 597, 94, 632, 35, 668, 33
Offset: 1

Views

Author

Antti Karttunen, Nov 23 2016

Keywords

Crossrefs

Inverse: A278511.
Cf. also A278504, A278506.

Formula

a(n) = (1/2) * ((c+r)^2 - r - 3*c + 2), where c = A278537(n) and r = A278538(n).
Showing 1-4 of 4 results.