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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A324377 a(0) = 0; for n > 0, a(n) = A000265(A005187(n)).

Original entry on oeis.org

0, 1, 3, 1, 7, 1, 5, 11, 15, 1, 9, 19, 11, 23, 25, 13, 31, 1, 17, 35, 19, 39, 41, 21, 23, 47, 49, 25, 53, 27, 7, 57, 63, 1, 33, 67, 35, 71, 73, 37, 39, 79, 81, 41, 85, 43, 11, 89, 47, 95, 97, 49, 101, 51, 13, 105, 109, 55, 7, 113, 29, 117, 119, 15, 127, 1, 65, 131, 67, 135, 137, 69, 71, 143, 145, 73, 149, 75, 19
Offset: 0

Views

Author

Antti Karttunen, Feb 28 2019

Keywords

Crossrefs

Programs

Formula

a(0) = 0; for n > 0, a(n) = A000265(A005187(n)) = A005187(n) / 2^A324379(n).
a(n) = A322821(A283477(n)).

A346237 Dirichlet inverse of A005187.

Original entry on oeis.org

1, -3, -4, 2, -8, 14, -11, 0, 0, 30, -19, -14, -23, 41, 38, 0, -32, -2, -35, -34, 49, 73, -42, 4, 17, 89, 14, -46, -54, -172, -57, 0, 88, 126, 109, 10, -71, 137, 110, 12, -79, -219, -82, -86, -6, 164, -89, 0, 26, -103, 158, -106, -102, -76, 199, 16, 170, 212, -113, 274, -117, 223, 16, 0, 240, -406, -131, -154, 201
Offset: 1

Views

Author

Antti Karttunen, Jul 13 2021

Keywords

Crossrefs

Programs

  • PARI
    up_to = 65537;
    DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(dA005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
    v346237 = DirInverseCorrect(vector(up_to,n,A005187(n)));
    A346237(n) = v346237[n];

Formula

a(n) = A346238(n) - A005187(n).

A379008 Square array A(n, k) = A294898(A246278(n, k)), read by falling antidiagonals; Difference A005187(n)-A000203(n) applied to the prime shift array.

Original entry on oeis.org

0, 0, 0, -2, 3, 2, 0, 2, 16, 3, 0, 10, 19, 38, 7, -6, 7, 88, 54, 104, 9, 1, 8, 33, 280, 113, 151, 14, 0, 16, 96, 65, 1192, 184, 268, 15, -5, 38, 44, 389, 152, 2009, 282, 336, 18, -4, 22, 464, 88, 1279, 207, 4600, 388, 502, 24, 5, 16, 142, 1996, 174, 2445, 345, 6470, 608, 806, 25, -14, 18, 174, 623, 13170, 257, 4834, 497, 11605, 833, 924, 33
Offset: 1

Views

Author

Antti Karttunen, Dec 14 2024

Keywords

Comments

Question: Are all columns increasing, and strictly increasing after the leftmost column?

Examples

			The top left corner of the array:
k=  |  1    2    3      4    5      6    7       8      9     10   11      12
2k= |  2    4    6      8   10     12   14      16     18     20   22      24
----+-------------------------------------------------------------------------
1   |  0,   0,  -2,     0,   0,    -6,   1,      0,    -5,    -4,   5,    -14,
2   |  0,   3,   2,    10,   7,     8,  16,     38,    22,    16,  18,     26,
3   |  2,  16,  19,    88,  33,    96,  44,    464,   142,   174,  58,    495,
4   |  3,  38,  54,   280,  65,   389,  88,   1996,   623,   469, 103,   2737,
5   |  7, 104, 113,  1192, 152,  1279, 174,  13170,  1516,  1717, 211,  14102,
6   |  9, 151, 184,  2009, 207,  2445, 257,  26172,  3208,  2756, 328,  31850,
7   | 14, 268, 282,  4600, 345,  4834, 439,  78295,  5406,  5916, 473,  82285,
8   | 15, 336, 388,  6470, 497,  7455, 533, 123071,  9035,  9501, 638, 141745,
9   | 18, 502, 608, 11605, 653, 14081, 784, 267115, 17773, 15097, 870, 324077,
Here 0's occur also after the first row. For example column 30, which corresponds with numbers 60, 315, 1925, 7007, 26741, ..., begins as -52, 0, 868, 4428, 19958, etc. See also A295296.
		

Crossrefs

Cf. A080085 (column 1, incremented by one).
Cf. also array A378979, and A324348 (another permutation of A294898).

Programs

  • PARI
    up_to = 11325; \\ = binomial(150+1,2)
    A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
    A294898(n) = (A005187(n)-sigma(n));
    A246278sq(row,col) = if(1==row,2*col, my(f = factor(2*col)); for(i=1, #f~, f[i,1] = prime(primepi(f[i,1])+(row-1))); factorback(f));
    A379008sq(row,col) = A294898(A246278sq(row,col));
    A379008list(up_to) = { my(v = vector(up_to), i=0); for(a=1,oo, for(col=1,a, i++; if(i > up_to, return(v)); v[i] = A379008sq(col,(a-(col-1))))); (v); };
    v379008 = A379008list(up_to);
    A379008(n) = v379008[n];

A279337 a(1) = 1, for n > 1, if n is even, a(n) = A055938(n/2), otherwise a(n) = A005187(a(A064989(n))).

Original entry on oeis.org

1, 2, 3, 5, 4, 6, 7, 9, 8, 12, 11, 13, 19, 14, 10, 17, 35, 20, 67, 21, 22, 24, 131, 27, 15, 28, 16, 29, 259, 30, 515, 33, 25, 36, 18, 37, 1027, 40, 46, 43, 2051, 44, 4099, 45, 23, 48, 8195, 51, 26, 52, 53, 55, 16387, 58, 41, 59, 70, 60, 32771, 61, 65539, 62, 39, 65, 47, 68, 131075, 69, 78, 72, 262147, 75, 524291, 76, 38, 77, 34, 80
Offset: 1

Views

Author

Antti Karttunen, Dec 10 2016

Keywords

Comments

For n > 1, a(n) = the number which is in the same position of array A256997 where n is located in array A246278.

Crossrefs

Inverse: A279336.
Cf. also A279339 (a variant).

Programs

Formula

a(1) = 1; for n > 1, if n is even, a(n) = A055938(n/2), otherwise a(n) = A005187(a(A064989(n))).
Other identities: For all n >= 2, a(n) = A256997(A252752(n)).

A283996 a(n) = n OR A005187(floor(n/2)), where OR is bitwise-or (A003986).

Original entry on oeis.org

0, 1, 3, 3, 7, 7, 6, 7, 15, 15, 10, 11, 14, 15, 15, 15, 31, 31, 18, 19, 22, 23, 23, 23, 30, 31, 31, 31, 29, 29, 30, 31, 63, 63, 34, 35, 38, 39, 39, 39, 46, 47, 47, 47, 45, 45, 46, 47, 62, 63, 63, 63, 53, 53, 54, 55, 61, 61, 62, 63, 60, 61, 63, 63, 127, 127, 66, 67, 70, 71, 71, 71, 78, 79, 79, 79, 77, 77, 78, 79, 94, 95, 95, 95, 85, 85, 86, 87, 93, 93, 94, 95
Offset: 0

Views

Author

Antti Karttunen, Mar 19 2017

Keywords

Crossrefs

Programs

  • Mathematica
    A[n_]:=2*n - DigitCount[2*n, 2, 1]; Table[BitOr[n, A[Floor[n/2]]], {n,0,100}] (* Indranil Ghosh, Mar 25 2017 *)
  • PARI
    b(n) = if(n<1, 0, b(n\2) + n%2);
    A(n) = 2*n - b(2*n);
    for(n=0, 100, print1(bitor(n, A(floor(n/2))),", ")) \\ Indranil Ghosh, Mar 25 2017
    
  • Python
    def A(n): return 2*n - bin(2*n)[2:].count("1")
    print([n|A(n//2) for n in range(101)]) # Indranil Ghosh, Mar 25 2017
  • Scheme
    (define (A283996 n) (A003986bi n (A005187 (floor->exact (/ n 2))))) ;; Where A003986bi implements bitwise-OR (A003986).
    

Formula

a(n) = n OR A005187(floor(n/2)), where OR is bitwise-or (A003986).
a(n) = A283997(n) + A283998(n).
a(n) = A005187(n) - A283998(n).

A283998 a(n) = n AND A005187(floor(n/2)), where AND is bitwise-and (A004198).

Original entry on oeis.org

0, 0, 0, 1, 0, 1, 4, 4, 0, 1, 8, 8, 8, 8, 10, 11, 0, 1, 16, 16, 16, 16, 18, 19, 16, 16, 18, 19, 24, 25, 26, 26, 0, 1, 32, 32, 32, 32, 34, 35, 32, 32, 34, 35, 40, 41, 42, 42, 32, 32, 34, 35, 48, 49, 50, 50, 48, 49, 50, 50, 56, 56, 56, 57, 0, 1, 64, 64, 64, 64, 66, 67, 64, 64, 66, 67, 72, 73, 74, 74, 64, 64, 66, 67, 80, 81, 82, 82, 80, 81, 82, 82, 88, 88, 88, 89
Offset: 0

Views

Author

Antti Karttunen, Mar 19 2017

Keywords

Crossrefs

Programs

  • Mathematica
    A[n_]:=2*n - DigitCount[2*n, 2, 1];Table[BitAnd[n, A[Floor[n/2]]], {n, 0, 100}] (* Indranil Ghosh, Mar 25 2017 *)
  • PARI
    b(n) = if(n<1, 0, b(n\2) + n%2);
    A(n) = 2*n - b(2*n);
    for(n=0, 100, print1(bitand(n, A(floor(n/2))),", ")) \\ Indranil Ghosh, Mar 25 2017
    
  • Python
    def A(n): return 2*n - bin(2*n)[2:].count("1")
    print([n&A(n//2) for n in range(101)]) # Indranil Ghosh, Mar 25 2017
  • Scheme
    (define (A283998 n) (A004198bi n (A005187 (floor->exact (/ n 2))))) ;; Where A004198bi implements bitwise-AND (A004198).
    

Formula

a(n) = n AND A005187(floor(n/2)), where AND is bitwise-and (A004198).
a(n) = A283996(n) - A283997(n).
a(n) = A005187(n) - A283996(n) = (A005187(n) - A283997(n))/2.

A283999 a(n) = A005187(n) XOR A006068(n), where XOR is bitwise-xor (A003987).

Original entry on oeis.org

0, 0, 0, 6, 0, 14, 14, 14, 0, 30, 30, 30, 30, 30, 18, 16, 0, 62, 62, 62, 62, 62, 50, 48, 62, 62, 34, 32, 34, 32, 44, 44, 0, 126, 126, 126, 126, 126, 114, 112, 126, 126, 98, 96, 98, 96, 108, 108, 126, 126, 66, 64, 66, 64, 76, 76, 66, 64, 92, 92, 92, 92, 92, 82, 0, 254, 254, 254, 254, 254, 242, 240, 254, 254, 226, 224, 226, 224, 236, 236, 254, 254, 194, 192, 194
Offset: 0

Views

Author

Antti Karttunen, Mar 20 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Table[BitXor[Fold[BitXor, n, Quotient[n, 2^Range[BitLength@ n - 1]]], 2 n - DigitCount[2 n, 2, 1]], {n, 0, 84}] (* Michael De Vlieger, Mar 20 2017, after Jan Mangaldan at A006068 *)
  • PARI
    b(n) = if(n<1, 0, b(n\2) + n%2);
    A(n) = 2*n - b(2*n);
    a(n) = if(n<2, n, 2*a(floor(n/2)) + (n%2 + a(floor(n/2))%2)%2);
    for(n=0, 110, print1(bitxor(A(n),a(n)),", ")) \\ Indranil Ghosh, Mar 25 2017
    
  • Python
    def A(n): return 2*n - bin(2*n)[2:].count("1")
    def a(n): return n if n<2 else 2*a(n//2) + (n%2 + a(n//2)%2)%2
    print([A(n)^a(n) for n in range(111)]) # Indranil Ghosh, Mar 25 2017
  • Scheme
    (define (A283999 n) (A003987bi (A005187 n) (A006068 n))) ;; Where A003987bi implements bitwise-XOR (A003987).
    

Formula

a(n) = A005187(n) XOR A006068(n), where XOR is bitwise-xor (A003987).
a(n) = A006068(2*n) XOR A283997(2*n).

A295655 a(n) = A000203(n) / A294896(n) = A000203(n) / gcd(A000203(n), A005187(n)).

Original entry on oeis.org

1, 1, 1, 1, 3, 6, 8, 1, 13, 1, 12, 14, 14, 24, 12, 1, 9, 39, 4, 21, 32, 36, 4, 30, 31, 6, 4, 56, 5, 9, 32, 1, 3, 9, 48, 13, 38, 60, 28, 15, 42, 32, 22, 84, 39, 9, 48, 62, 3, 93, 36, 98, 9, 15, 24, 120, 8, 45, 60, 42, 62, 96, 13, 1, 21, 72, 68, 63, 32, 144, 12, 195, 74, 114, 62, 140, 16, 21, 80, 93, 121, 18, 14
Offset: 1

Views

Author

Antti Karttunen, Nov 25 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Array[#1/GCD[#1, #2] & @@ {DivisorSigma[1, #], IntegerExponent[(2 #)!, 2]} &, 83] (* Michael De Vlieger, Nov 26 2017 *)

Formula

a(n) = A000203(n) / A294896(n) = A000203(n) / gcd(A000203(n), A005187(n)).

A295656 a(n) = A005187(n) / A294896(n) = A005187(n) / gcd(A000203(n), A005187(n)).

Original entry on oeis.org

1, 1, 1, 1, 4, 5, 11, 1, 16, 1, 19, 11, 23, 25, 13, 1, 16, 34, 7, 19, 39, 41, 7, 23, 47, 7, 5, 53, 9, 7, 57, 1, 4, 11, 67, 10, 71, 73, 37, 13, 79, 27, 41, 85, 43, 11, 89, 47, 5, 97, 49, 101, 17, 13, 35, 109, 11, 56, 113, 29, 117, 119, 15, 1, 32, 65, 131, 67, 45, 137, 23, 142, 143, 145, 73, 149, 25, 19, 153, 79, 159, 23, 27
Offset: 1

Views

Author

Antti Karttunen, Nov 25 2017

Keywords

Crossrefs

Formula

a(n) = A005187(n) / A294896(n) = A005187(n) / gcd(A000203(n), A005187(n)).

A318445 a(n) = Sum_{d|n, dA005187(d).

Original entry on oeis.org

0, 1, 1, 4, 1, 8, 1, 11, 5, 12, 1, 25, 1, 15, 13, 26, 1, 34, 1, 37, 16, 23, 1, 62, 9, 27, 21, 47, 1, 70, 1, 57, 24, 36, 20, 97, 1, 39, 28, 90, 1, 93, 1, 71, 55, 46, 1, 139, 12, 77, 37, 83, 1, 118, 28, 115, 40, 58, 1, 193, 1, 61, 71, 120, 32, 142, 1, 109, 47, 133, 1, 228, 1, 75, 86, 119, 31, 164, 1, 199, 71, 83, 1, 256, 41
Offset: 1

Views

Author

Antti Karttunen, Aug 26 2018

Keywords

Crossrefs

Programs

  • PARI
    A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
    A318445(n) = sumdiv(n,d,(dA005187(d));

Formula

a(n) = Sum_{d|n, dA005187(d).
a(n) = A318446(n) - A005187(n).
a(n) = A211779(n) + A318447(n).
a(n) = A293447(A293214(n)).
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