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.

A256490 First differences of A257512: a(n) = A257512(n+1) - A257512(n).

Original entry on oeis.org

8, 7, 9, 7, 13, 2, 10, 7, 13, 2, 14, 8, 7, 2, 11, 7, 13, 2, 14, 8, 7, 2, 15, 8, 7, 9, 7, 14, 1, 2, 12, 7, 13, 2, 14, 8, 7, 2, 15, 8, 7, 9, 7, 14, 1, 2, 16, 8, 7, 9, 7, 14, 1, 10, 7, 14, 1, 15, 8, 7, 1, 2, 13, 7, 13, 2, 14, 8, 7, 2, 15, 8, 7, 9, 7, 14, 1, 2, 16, 8, 7, 9, 7, 14, 1, 10, 7, 14, 1, 15, 8, 7, 1
Offset: 1

Views

Author

Antti Karttunen, May 03 2015

Keywords

Comments

It seems that for all n >= 1, Sum_{k=1 .. 2^n} a(k) = 2^(n+3) - 1 = A000225(n+3).

Crossrefs

Programs

Formula

a(n) = A257512(n+1) - A257512(n).

A257508 Next-to-leaf vertices in binary beanstalk; Numbers n for which A257265(n) = 1.

Original entry on oeis.org

1, 3, 4, 7, 10, 11, 15, 18, 22, 23, 25, 26, 31, 34, 38, 39, 41, 46, 47, 49, 50, 54, 56, 57, 63, 66, 70, 71, 73, 78, 79, 81, 82, 86, 88, 94, 95, 97, 98, 102, 104, 105, 110, 113, 116, 117, 119, 120, 127, 130, 134, 135, 137, 142, 143, 145, 146, 150, 152, 158, 159, 161, 162, 166, 168, 169, 174, 177, 180, 181
Offset: 1

Views

Author

Antti Karttunen, May 03 2015

Keywords

Comments

Numbers n for which A257265(n) = 1, in other words, numbers n for which a descendant leaf nearest to n in binary beanstalk is one edge away.
Numbers n such that either A079559(A213723(n)) or A079559(A213724(n)) (or both) are zero.
Equal to A257507 with duplicate terms removed.

Examples

			3 is present because it has an immediate leaf-child 5, as A011371(5) = 3.
4 is present because it has an immediate leaf-child 6, as A011371(6) = 4.
10 is present because it has two immediate leaf-children, 12 and 13, as A011371(12) = A011371(13) = 10.
See also Paul Tek's illustration.
		

Crossrefs

Positions of 1's in A257265.
Subsequence of A005187.
Cf. A011371, A079559, A213723, A213724, A257507, A257509, A257512 (a subsequence).

Programs

  • Haskell
    a257508 n = a257508_list !! (n-1)
    a257508_list = filter ((== 1) . a257265) [0..]
    -- Reinhard Zumkeller, May 06 2015

A257507 Row 2 of A257264: a(n) = A011371(A055938(n)).

Original entry on oeis.org

1, 3, 4, 7, 10, 10, 11, 15, 18, 18, 22, 23, 25, 25, 26, 31, 34, 34, 38, 39, 41, 41, 46, 47, 49, 50, 54, 54, 56, 56, 57, 63, 66, 66, 70, 71, 73, 73, 78, 79, 81, 82, 86, 86, 88, 88, 94, 95, 97, 98, 102, 102, 104, 105, 110, 110, 113, 116, 117, 117, 119, 119, 120, 127, 130, 130, 134, 135, 137, 137, 142, 143, 145, 146
Offset: 1

Views

Author

Antti Karttunen, May 03 2015

Keywords

Comments

The sequence gives the parent node of each leaf-vertex (A055938) in binary beanstalk.

Examples

			Terms of A055938 are the leaf-nodes in Paul Tek's illustration. This sequence gives the corresponding parent-node (in that illustration a node immediately below where the arrow points), for each term of A055938[1..]: 2, 5, 6, 9, 12, 13, 14, ...
As A055938(4) = 9, and 9's parent node is 7 (because A011371(9) = 7), a(4) = 7.
As A055938(5) = 12, and 12's parent node is 10, a(5) = 10.
As A055938(6) = 13, and 13's parent node is 10, a(6) = 10.
		

Crossrefs

Row 2 of A257264.
Cf. A257508 (same sequence with duplicates removed), A257512 (the terms which occur twice).

Programs

Formula

a(n) = A011371(A055938(n)).

A262903 Numbers that are not leaves but all of whose children are leaves in the tree generated by edge-relation A049820(child) = parent.

Original entry on oeis.org

4, 5, 14, 16, 32, 41, 44, 77, 80, 92, 101, 110, 119, 128, 139, 148, 158, 161, 169, 176, 191, 192, 199, 215, 224, 227, 234, 238, 249, 262, 264, 277, 296, 311, 317, 327, 350, 351, 352, 360, 363, 382, 385, 389, 392, 395, 396, 411, 427, 430, 437, 448, 449, 461, 464, 483, 488, 518, 523, 531, 532, 542, 552, 561, 568, 570, 577, 579, 600, 601, 613, 619, 632, 634, 636, 645, 648, 659, 665, 666, 671, 682, 683, 696, 705, 723
Offset: 1

Views

Author

Antti Karttunen, Oct 06 2015

Keywords

Comments

Numbers n for which A060990(n) > 0 and A060990(n) = A262900(n).
Numbers n for which A262695(n) = 2.

Crossrefs

Subsequence of A262901 and A236562.
No common terms with A259934.
Cf. also A257512.
Showing 1-4 of 4 results.