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 1-7 of 7 results.

A283473 Numbers n for which A004001(n) = A283470(n).

Original entry on oeis.org

1, 2, 5, 11, 12, 23, 24, 25, 26, 27, 50, 51, 52, 53, 54, 55, 56, 57, 58, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 477, 478, 479, 480, 481, 482, 483, 484, 485, 486, 487, 488, 489, 490, 491, 492, 493, 494, 495
Offset: 1

Views

Author

Antti Karttunen, Mar 18 2017

Keywords

Comments

Equally, numbers n such that A004001(n) = A283469(n).

Crossrefs

Positions of zeros in A283472.

Programs

  • Mathematica
    a[n_] := a[n] = If[n <= 2, 1, a[a[n - 1]] + a[n - a[n - 1]]]; With[{nn = 500}, Function[s, Select[Range@ nn, a@ # == s[[#]] &]]@ Table[BitXor[a[#], a[n - #]] &@ a[n - 1] + Boole[n <= 2], {n, nn}]] (* Michael De Vlieger, Mar 18 2017, after Robert G. Wilson v at A004001 *)

A283469 a(n) = A004001(A004001(n-1)) OR A004001(n-A004001(n-1)), a(1) = a(2) = 1.

Original entry on oeis.org

1, 1, 1, 1, 3, 2, 2, 2, 3, 3, 7, 7, 4, 4, 4, 4, 5, 5, 7, 7, 7, 7, 14, 14, 15, 15, 15, 8, 8, 8, 8, 8, 9, 9, 11, 11, 13, 13, 14, 15, 14, 14, 15, 15, 15, 15, 15, 15, 15, 29, 29, 30, 30, 30, 31, 31, 31, 31, 16, 16, 16, 16, 16, 16, 17, 17, 19, 19, 21, 21, 21, 23, 22, 23, 26, 26, 27, 27, 27, 27, 30, 31, 31, 31, 31, 31, 31, 30, 31, 31, 31, 31, 31
Offset: 1

Views

Author

Antti Karttunen, Mar 18 2017

Keywords

Crossrefs

Cf. A003986, A283470, A283472, A283473 (positions where coincides with A004001).

Programs

Formula

a(1) = a(2) = 1; for n > 2, a(n) = A004001(A004001(n-1)) OR A004001(A080677(n-1)), where OR is bitwise-or (A003986)
Other identities. For all n >= 1:
a(n) = A283470(n) + A283472(n).
A004001(n) = a(n) + A283472(n).

A283471 Numbers n > 2 such that A004001(A004001(n-1)) = A004001(n-A004001(n-1)).

Original entry on oeis.org

3, 4, 6, 7, 8, 10, 13, 14, 15, 16, 18, 28, 29, 30, 31, 32, 34, 59, 60, 61, 62, 63, 64, 66, 122, 123, 124, 125, 126, 127, 128, 130, 249, 250, 251, 252, 253, 254, 255, 256, 258, 504, 505, 506, 507, 508, 509, 510, 511, 512, 514, 1015, 1016, 1017, 1018, 1019, 1020, 1021, 1022, 1023, 1024, 1026, 2038, 2039, 2040, 2041, 2042, 2043, 2044, 2045
Offset: 1

Views

Author

Antti Karttunen, Mar 18 2017

Keywords

Comments

Equally, numbers n > 2 for which A004001(A004001(n-1)) = A004001(A080677(n-1)).

Crossrefs

Positions of zeros in A283468 and A283470.
Subsequence of A283482.

Programs

  • Mathematica
    a[n_] := a[n] = If[n <= 2, 1, a[a[n - 1]] + a[n - a[n - 1]]]; Select[Range[3, 2^11], Function[n, a[#] == a[n - #] &@ a[n - 1]]] (* Michael De Vlieger, Mar 18 2017, after Robert G. Wilson v at A004001 *)

A283472 a(n) = A004001(A004001(n-1)) AND A004001(n-A004001(n-1)), a(1) = a(2) = 0.

Original entry on oeis.org

0, 0, 1, 1, 0, 2, 2, 2, 2, 3, 0, 0, 4, 4, 4, 4, 4, 5, 4, 5, 5, 6, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 9, 8, 9, 8, 8, 8, 8, 10, 10, 10, 11, 11, 12, 12, 12, 13, 0, 0, 0, 0, 0, 0, 0, 0, 0, 16, 16, 16, 16, 16, 16, 16, 17, 16, 17, 16, 17, 17, 16, 18, 18, 16, 16, 16, 17, 18, 18, 16, 16, 16, 17, 17, 17, 18, 20, 20, 20, 21, 22, 22, 24, 24, 24, 24
Offset: 1

Views

Author

Antti Karttunen, Mar 18 2017

Keywords

Crossrefs

Cf. A004001, A004198, A283469, A283470, A283473 (positions of zeros).

Programs

Formula

a(1) = a(2) = 0; for n > 2, a(n) = A004001(A004001(n-1)) AND A004001(A080677(n-1)), where AND is bitwise-and (A004198).
Other identities. For all n >= 1:
a(n) = A283469(n) - A283470(n).
A004001(n) = A283469(n) + a(n) = A283470(n) + 2*a(n).

A283468 a(n) = A004001(A004001(n-1)) - A004001(n-A004001(n-1)), a(1) = a(2) = 1.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Mar 18 2017

Keywords

Comments

The only negative terms seem to be -1's, occurring as a(1+(2^n)), for n >= 2.

Crossrefs

Cf. A004001, A080677, A283471 (positions of zeros), A283469, A283470, A283472.
Cf. also A283655.

Programs

Formula

a(1) = a(2) = 1; for n > 2, a(n) = A004001(A004001(n-1)) - A004001(A080677(n-1)).

A286541 Compound filter (the left & right summand of Hofstadter-Conway $10000 sequence): a(n) = P(A004001(A004001(n-1)), A004001(n-A004001(n-1))), where P(n,k) is sequence A000027 used as a pairing function, with a(1) = a(2) = 0.

Original entry on oeis.org

0, 0, 1, 1, 2, 5, 5, 5, 8, 13, 19, 19, 25, 25, 25, 25, 32, 41, 51, 62, 62, 73, 86, 86, 99, 99, 99, 113, 113, 113, 113, 113, 128, 145, 163, 182, 202, 202, 222, 244, 267, 267, 290, 315, 315, 340, 340, 340, 366, 394, 394, 422, 422, 422, 451, 451, 451, 451, 481, 481, 481, 481, 481, 481, 512, 545, 579, 614, 650, 687, 687, 724, 763, 803, 844, 844, 885, 928, 972, 972
Offset: 1

Views

Author

Antti Karttunen, May 18 2017

Keywords

Crossrefs

Programs

Formula

a(1) = a(2) = 0, for n > 2, a(n) = (1/2)*(2 + ((A004001(A004001(n-1))+A004001(n-A004001(n-1)))^2) - A004001(A004001(n-1)) - 3*A004001(n-A004001(n-1))).

A283677 a(n) = lcm(b(b(n)), b(n-b(n)+1)) where b(n) = A004001(n).

Original entry on oeis.org

1, 1, 1, 2, 2, 2, 2, 6, 3, 12, 12, 4, 4, 4, 4, 20, 5, 30, 35, 35, 42, 24, 24, 56, 56, 56, 8, 8, 8, 8, 8, 72, 9, 90, 99, 36, 36, 60, 130, 70, 70, 154, 165, 165, 60, 60, 60, 195, 208, 208, 112, 112, 112, 240, 240, 240, 240, 16, 16, 16, 16, 16, 16, 272, 17, 306, 323, 340, 357, 357, 126, 198, 414, 72, 72, 456, 475, 494
Offset: 1

Views

Author

Altug Alkan, Mar 14 2017

Keywords

Comments

See the order of certain subsequences in scatterplot link.

Examples

			a(4) = lcm(A004001(A004001(4)), A004001(4-A004001(4)+1)) = lcm(1, 2) = 2.
		

Crossrefs

Cf. also A283470, A283673.

Programs

  • Mathematica
    b[1] = b[2] = 1; b[n_] := b[n] = b[b[n - 1]] + b[n - b[n - 1]]; Table[LCM[b[b[n]], b[n + 1 - b[n]]], {n, 1, 78}] (* Indranil Ghosh, Mar 14 2017 *)
  • PARI
    a=vector(1000); a[1]=a[2]=1; for(n=3, #a, a[n]=a[a[n-1]]+a[n-a[n-1]]); va = vector(1000, n, lcm(a[a[n]], a[n+1-a[n]]))
    
  • Scheme
    (define (A283677 n) (lcm (A004001 (A004001 n)) (A004001 (+ 1 (- n (A004001 n)))))) ;; (Code for A004001 given under that entry). - Antti Karttunen, Mar 18 2017

Formula

a(n) = lcm(A004001(A004001(n)), A004001(A080677(n))). - Antti Karttunen, Mar 18 2017
Showing 1-7 of 7 results.