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.

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A263266 Inverse permutation to A263265: a(0) = 0; for n >= 1, a(n) = A263259(n) + A263260(A155043(n)-1) - 1.

Original entry on oeis.org

0, 1, 2, 3, 4, 6, 5, 11, 7, 8, 9, 12, 10, 15, 13, 16, 17, 20, 14, 26, 18, 27, 19, 30, 21, 22, 23, 34, 24, 38, 25, 46, 28, 47, 29, 50, 39, 54, 31, 55, 32, 59, 33, 67, 35, 60, 36, 68, 37, 40, 41, 74, 42, 81, 43, 82, 44, 88, 48, 95, 45, 103, 51, 96, 97, 108, 52, 114, 56, 115, 57, 120, 49, 128, 61, 121, 62, 138, 63, 145, 64, 69, 70, 75, 53
Offset: 0

Views

Author

Antti Karttunen, Nov 24 2015

Keywords

Crossrefs

Inverse: A263265.
Cf. A263281 (fixed points).
Differs from A263268 for the first time at n=38, where a(38) = 31, while A263268(38) = 32.

Programs

Formula

a(0) = 0; for n >= 1, a(n) = A263259(n) + A263260(A155043(n)-1) - 1.

A262505 Distance between the positions of the first and the last occurrence of n in A155043: a(n) = A262503(n) - A261089(n).

Original entry on oeis.org

0, 1, 3, 7, 11, 9, 13, 15, 19, 21, 31, 41, 49, 59, 67, 77, 81, 87, 55, 57, 65, 59, 63, 67, 77, 79, 89, 37, 27, 33, 37, 47, 55, 65, 67, 71, 85, 99, 65, 67, 77, 89, 93, 103, 95, 105, 109, 117, 121, 131, 135, 115, 117, 119, 133, 133, 153, 133, 143, 141, 147, 159, 175, 181, 201, 205, 223, 239, 245, 249, 259, 275, 269, 271, 273, 271, 289, 303, 77
Offset: 0

Views

Author

Antti Karttunen, Sep 25 2015

Keywords

Crossrefs

Cf. A262508 (positions of zeros).
Cf. A262507 (the number of occurrences of n in A155043).

Programs

Formula

a(n) = A262503(n) - A261089(n).
a(n) = A261103(n) + A262506(n).

A263078 a(n) = greatest k for which A155043(n+k) < A155043(n); a(n) = A263077(n)-n.

Original entry on oeis.org

-1, -2, -1, -2, 1, -4, 5, -2, -3, -4, 1, -6, 5, -2, 3, 2, 5, -6, 11, -2, 9, -4, 11, -2, -3, -4, 15, -6, 19, -8, 29, -2, 27, -4, 37, 12, 47, -4, 45, -6, 55, -8, 65, -2, 51, -4, 61, -6, -1, -2, 69, -4, 79, -6, 77, -8, 83, 2, 81, -12, 79, 10, 77, 76, 75, 6, 73, 16, 71, 14, 69, -12, 67, 22, 65, 20, 73, 18, 77, 16, 27, 26, 37, -12, 35, 34, 45, 20, 51, 18, 49, 40, 47, 26, 45, -12, 43, 42, 41, 40, 39, 30
Offset: 1

Views

Author

Antti Karttunen, Oct 09 2015

Keywords

Examples

			For n=1 we have A049820(1) = 0, thus A155043(1) = 1, and 0 is the only (and thus the largest) number from which zero can be reached with less steps (namely in zero steps, A155043(0) = 0), thus a(1) = 0 - 1 = -1.
For n=7, we have A155043(7) = 4 [as A049820(7) = 5, A049820(5) = 3, A049820(3) = 1, A049820(1) = 0], but there exists x=12 for which we have A049820(12) = 6, A049820(6) = 2, A049820(2) = 0, and this is the largest x such that A155043(x) < A155043(7), thus a(7) = 12 - 7 = 5.
		

Crossrefs

Cf. A263079 (indices of the negative terms), A263080 (of the positive terms).

Programs

  • Mathematica
    a[0] = 0; a[n_] := a[n] = 1 + a[n - DivisorSigma[0, n]]; Table[k = 3 n;
    While[a@ k >= a@ n, k--]; k - n, {n, 102}] (* Michael De Vlieger, Oct 13 2015 *)
  • PARI
    A263078 = n -> A263077(n) - n;
    for(n=1,124340,write("b263078.txt",n," ",A263078(n)));
    \\ Other code as in A263077

Formula

a(n) = A263077(n)-n.

A263079 Numbers n for which there does not exist any x > n such that A155043(x) < A155043(n).

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 9, 10, 12, 14, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, 38, 40, 42, 44, 46, 48, 49, 50, 52, 54, 56, 60, 72, 84, 96, 104, 108, 120, 128, 132, 136, 140, 142, 144, 150, 152, 156, 160, 162, 168, 170, 180, 182, 184, 186, 188, 190, 192, 194, 198, 200, 204, 208, 210, 216, 220, 225, 228, 240, 248, 252, 260, 264, 276, 280, 288, 296, 300, 308, 312, 320, 328, 340, 352, 360
Offset: 1

Views

Author

Antti Karttunen, Oct 09 2015

Keywords

Comments

Numbers n for which A263077(n) < n.
Numbers n for which A263078(n) is negative.
Numbers n at which point A155043(n) is the greatest lower bound for the rest of its terms from A155043(n) onward.

Examples

			1 is present because A049820(1) = 0, thus A155043(1) = 1, while all the larger numbers require at least the same number of steps to reach zero.
		

Crossrefs

Programs

A263259 a(n) = number of integers k <= n for which A155043(k) = A155043(n).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Nov 24 2015

Keywords

Comments

a(n) = one-based index of n in row A155043(n) of table A263265.

Crossrefs

Formula

Other identities. For all n >= 0:
a(A261089(n)) = 1.
a(A262503(n)) = A262507(n).
A263265(A155043(n), a(n)) = n.

A263080 Numbers n for which there exists x > n such that A155043(x) < A155043(n); numbers n for which A263078(n) is positive.

Original entry on oeis.org

5, 7, 11, 13, 15, 16, 17, 19, 21, 23, 27, 29, 31, 33, 35, 36, 37, 39, 41, 43, 45, 47, 51, 53, 55, 57, 58, 59, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 97, 98, 99, 100, 101, 102, 103, 105, 106, 107, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 121
Offset: 1

Views

Author

Antti Karttunen, Oct 09 2015

Keywords

Examples

			5 is present, because if we start iterating A049820 from it as: A049820(5) = 3, A049820(3) = 1, A049820(1) = 0, we get a path of length 3 to reach zero, thus A155043(5) = 3. On the other hand, if we start from 6, the path is one step shorter: A049820(6) = 2, A049820(2) = 0 [i.e., A155043(6) = 2], thus there exists a number larger than 5 which results a shorter path to zero.
		

Crossrefs

Programs

  • Mathematica
    a[0] = 0; a[n_] := a[n] = 1 + a[n - DivisorSigma[0, n]]; Position[Table[k = 3 n; While[a@ k >= a@ n, k--]; k - n, {n, 121}], Integer?Positive] // Flatten (* _Michael De Vlieger, Oct 13 2015 *)
  • PARI
    n=0; i=0; while(i < 10000, n++; if((A263077(n) > n), i++; write("b263080.txt",i," ",n)));
    \\ Other code as in A263077.
    
  • Scheme
    ;; With Antti Karttunen's IntSeq-library.
    (define A263080 (MATCHING-POS 1 1 (COMPOSE positive? A263078)))

A263081 a(n) = largest k for which A155043(k) < A262508(n); a(n) = A262509(n) + A262909(n).

Original entry on oeis.org

124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 124340, 24684000, 24684000, 24684000, 24684000, 24684000, 24684000, 24684000
Offset: 1

Views

Author

Antti Karttunen, Oct 09 2015

Keywords

Comments

a(n) = largest k for which A155043(k) < A155043(A262509(n)).
If a(n) > A262509(n) then it must be a leaf (see comments in A262909 for why). Particularly, we have A045765(40722) = 124340, A045765(8191770) = 24684000.
Terms of sequence (together with the corresponding values in A262508) give particularly clean values for the boundaries that are used for example in the C++-program which computes A262896.

Crossrefs

Programs

Formula

a(n) = A263077(A262509(n)).
a(n) = A262509(n) + A262909(n).

A263280 a(n) = A262507(n) - A263279(n); number of integers k > A259934(n) for which A155043(k) = n = A155043(A259934(n)).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Nov 24 2015

Keywords

Comments

a(n) gives the distance of position of A259934(n) at row n of table A263265 from its right edge.

Crossrefs

Programs

Formula

a(n) = A262507(n) - A263279(n).

A262521 Numbers where A262520 takes a negative value; numbers n for which A155043(2n) > A155043(2n + 1).

Original entry on oeis.org

112, 113, 544, 545, 684, 760, 930, 1306, 1514, 1522, 1624, 1625, 2048, 2386, 2389, 2393, 2399, 2402, 2818, 2827, 2966, 2969, 3280, 3281, 3791, 3797, 3878, 4324, 4326, 4328, 4330, 4331, 4333, 4334, 4336, 4340, 4342, 4346, 4352, 5513, 5515, 5519, 5521, 5527, 5531, 5724, 5726, 6050, 6161, 6165, 6167, 6168, 6169, 6172, 6173, 6176, 6177, 6179, 6181, 6183, 6184, 6185, 6272
Offset: 1

Views

Author

Antti Karttunen, Oct 02 2015

Keywords

Crossrefs

A262909 a(n) = greatest k such that A155043(k+A262509(n)) < A155043(A262509(n)).

Original entry on oeis.org

5197, 5193, 5177, 5115, 5113, 4419, 4417, 4259, 4245, 4243, 4239, 4059, 4047, 3991, 3941, 3633, 3593, 3449, 3445, 3437, 3423, 3421, 2897, 2789, 2517, 2261, 2079, 2077, 2067, 2063, 1527, 1379, 1135, 1127, 1117, 1103, 1083, 575, 23457, 23451, 21689, 21671, 20241, 19003, 18977, 18649, 18063, 18019, 14853, 14159, 13659, 12707, 11681, 10993, 10991, 10297, 10281, 9151, 9149, 9145, 9111, 8897, 8535, 8147, 6835, 6813, 5539, 5537
Offset: 1

Views

Author

Antti Karttunen, Oct 09 2015

Keywords

Comments

a(n) = largest k such that A155043(k+A262509(n)) < A262508(n).
There might occur also negative terms, but no zeros.
For all terms a(n) > 0, a(n)+A262509(n) = A263081(n) is by necessity one of the leaves (A045765) in the tree generated by edge-relation A049820(child) = parent. See also comments in A262908.

Crossrefs

Formula

a(n) = A263078(A262509(n)).
a(n) = A263081(n) - A262509(n).
Other identities. For all n >= 1:
a(n) >= A262908(n).
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