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 1-10 of 51 results. Next

A318878 Sum of A083254(d) for all such divisors d of n for which A083254(d) > 0.

Original entry on oeis.org

1, 1, 2, 1, 4, 2, 6, 1, 5, 4, 10, 2, 12, 6, 6, 1, 16, 5, 18, 4, 10, 10, 22, 2, 19, 12, 14, 6, 28, 6, 30, 1, 18, 16, 22, 5, 36, 18, 22, 4, 40, 10, 42, 10, 12, 22, 46, 2, 41, 19, 30, 12, 52, 14, 38, 6, 34, 28, 58, 6, 60, 30, 22, 1, 46, 18, 66, 16, 42, 22, 70, 5, 72, 36, 26, 18, 58, 22, 78, 4, 41, 40, 82, 10, 62, 42, 54, 10, 88, 12, 70, 22, 58, 46, 70, 2
Offset: 1

Views

Author

Antti Karttunen, Sep 05 2018

Keywords

Examples

			n = 105 has divisors [1, 3, 5, 7, 15, 21, 35, 105]. When A083254 is applied to them, we obtain [1, 1, 3, 5, 1, 3, 13, -9]. Summing the positive numbers present, we get a(105) = 1+1+3+5+1+3+13 = 27.
		

Crossrefs

Programs

  • PARI
    A318878(n) = sumdiv(n,d,d=(2*eulerphi(d))-d; (d>0)*d);

Formula

a(n) = Sum_{d|n} [A083254(d) > 0]*A083254(d), where A083254(n) = 2*phi(n) - n, and [ ] are the Iverson brackets.
a(n) = A318879(n) + A033879(n).

A324052 a(n) = A083254(A005940(1+n)).

Original entry on oeis.org

1, 0, 1, 0, 3, -2, 3, 0, 5, -2, 1, -4, 15, -6, 9, 0, 9, -2, 3, -4, 13, -14, 3, -8, 35, -10, 5, -12, 75, -18, 27, 0, 11, -2, 7, -4, 25, -18, 9, -8, 43, -22, -9, -28, 65, -42, 9, -16, 99, -14, 21, -20, 91, -70, 15, -24, 245, -50, 25, -36, 375, -54, 81, 0, 15, -2, 9, -4, 31, -26, 21, -8, 53, -30, -5, -36, 125, -54, 27, -16, 97, -34, 9
Offset: 0

Views

Author

Antti Karttunen, Feb 18 2019

Keywords

Crossrefs

Programs

  • PARI
    A324052(n) = { my(m1=1,m2=2,p=2); while(n, if(!(n%2), p=nextprime(1+p), m1 *= p; m2 *= (p-(1==(n%4)))); n>>=1); (m2-m1); };
    
  • PARI
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t }; \\ From A005940
    A083254(n) = (2*eulerphi(n)-n);
    A324052(n) = A083254(A005940(1+n));

Formula

a(n) = A083254(A005940(1+n)).
a(n) = 2*A290077(n) - A005940(1+n).
For n >= 1, a(n) = A324182(A054429(n)).
For n >= 1, a((2^n)-1) = 0.

A324103 a(1) = 0; for n > 1, a(n) = A083254(A156552(n)).

Original entry on oeis.org

0, 1, 0, 1, 0, 3, 0, 5, -2, 3, 0, 9, 0, 15, -2, 1, 0, 11, 0, 17, -6, 7, 0, 21, -4, 31, -2, 13, 0, 3, 0, 29, -2, 39, -4, 9, 0, 255, -26, 9, 0, 35, 0, 65, -2, 135, 0, 45, -8, 15, -34, 129, 0, 27, -12, 69, -90, 575, 0, 41, 0, 679, -2, 9, -4, 19, 0, 173, -2, 39, 0, 25, 0, 3583, -2, 301, -8, 83, 0, 77, -14, 2727, 0, 5, -52, 8703, -378, 9, 0, 3
Offset: 1

Views

Author

Antti Karttunen, Feb 18 2019

Keywords

Crossrefs

Programs

Formula

a(1) = 0; for n > 1, a(n) = A083254(A156552(n)).
a(n) = 2*A324104(n) - A156552(n).

A323898 Lexicographically earliest sequence such that a(i) = a(j) => A000120(i) = A000120(j) and A083254(i) = A083254(j), for all i, j >= 1.

Original entry on oeis.org

1, 2, 3, 2, 4, 5, 6, 2, 4, 5, 7, 8, 9, 10, 11, 2, 12, 13, 14, 8, 15, 10, 16, 17, 18, 10, 19, 20, 21, 22, 23, 2, 24, 5, 25, 26, 27, 10, 19, 17, 28, 29, 30, 20, 31, 32, 33, 34, 27, 35, 36, 20, 37, 38, 39, 40, 41, 32, 42, 43, 44, 45, 46, 2, 47, 48, 49, 8, 50, 51, 52, 53, 54, 10, 55, 20, 56, 57, 58, 34, 59, 10, 60, 61, 56, 32, 39, 40, 62, 63, 64, 65, 66, 45, 67, 68, 69, 70, 16
Offset: 1

Views

Author

Antti Karttunen, Feb 09 2019

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A000120(n), A083254(n)].

Crossrefs

Programs

  • PARI
    up_to = 65537;
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    A083254(n) = (2*eulerphi(n)-n);
    A323898aux(n) = [hammingweight(n), A083254(n)];
    v323898 = rgs_transform(vector(up_to,n,A323898aux(n)));
    A323898(n) = v323898[n];

Formula

a(2^n) = 2 for all n >= 1.

A323912 Dirichlet inverse of A083254(n), where A083254(n) = 2*phi(n) - n.

Original entry on oeis.org

1, 0, -1, 0, -3, 2, -5, 0, -2, 2, -9, 4, -11, 2, 5, 0, -15, 2, -17, 4, 7, 2, -21, 8, -6, 2, -4, 4, -27, -2, -29, 0, 11, 2, 17, 8, -35, 2, 13, 8, -39, -6, -41, 4, 8, 2, -45, 16, -10, -2, 17, 4, -51, 0, 29, 8, 19, 2, -57, 4, -59, 2, 12, 0, 35, -14, -65, 4, 23, -10, -69, 24, -71, 2, 4, 4, 47, -18, -77, 16, -8, 2, -81, -4, 47, 2, 29, 8, -87, 4
Offset: 1

Views

Author

Antti Karttunen, Feb 12 2019

Keywords

Crossrefs

Sequences that appear in the convolution formulas: A002033, A023900, A046692, A055615, A067824, A074206, A101035, A130054, A174725, A191161, A253249, A323910 (Möbius transform), A328722, A330575.

Programs

  • PARI
    up_to = 16384;
    DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(dA083254(n) = (2*eulerphi(n)-n);
    v323912 = DirInverse(vector(up_to,n,A083254(n)));
    A323912(n) = v323912[n];
    
  • PARI
    A083254(n) = (2*eulerphi(n)-n);
    memoA323912 = Map();
    A323912(n) = if(1==n,1,my(v); if(mapisdefined(memoA323912,n,&v), v, v = -sumdiv(n,d,if(dA083254(n/d)*A323912(d),0)); mapput(memoA323912,n,v); (v))); \\ Antti Karttunen, Nov 22 2024

Formula

a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, dA083254(n/d) * a(d).
From Antti Karttunen, Nov 22 2024: (Start)
Following convolution formulas were conjectured for this sequence by Sequence Machine, with each one giving the first 10000 terms correctly. The first one is certainly true, because A083254 is Möbius transform of A033879:
a(n) = Sum_{d|n} A323910(d).
a(n) = Sum_{d|n} A023900(d)*A074206(n/d) = Sum_{d|n} A002033(d-1)*A023900(n/d).
a(n) = Sum_{d|n} A055615(d)*A067824(n/d)
a(n) = Sum_{d|n} A046692(d)*A253249(n/d)
a(n) = Sum_{d|n} A130054(d)*A174725(n/d)
a(n) = Sum_{d|n} A101035(d)*A330575(n/d)
a(n) = Sum_{d|n} A191161(d)*A328722(n/d)
(End)

A324182 a(n) = A083254(A163511(n)), where A083254(n) = 2*phi(n) - n, the Möbius transform of the deficiency of n.

Original entry on oeis.org

1, 0, 0, 1, 0, 3, -2, 3, 0, 9, -6, 15, -4, 1, -2, 5, 0, 27, -18, 75, -12, 5, -10, 35, -8, 3, -14, 13, -4, 3, -2, 9, 0, 81, -54, 375, -36, 25, -50, 245, -24, 15, -70, 91, -20, 21, -14, 99, -16, 9, -42, 65, -28, -9, -22, 43, -8, 9, -18, 25, -4, 7, -2, 11, 0, 243, -162, 1875, -108, 125, -250, 1715, -72, 75, -350, 637, -100, 147, -98, 1089
Offset: 0

Views

Author

Antti Karttunen, Feb 18 2019

Keywords

Crossrefs

Cf. A054429, A083254, A163511, A324052, A324183, A324184, A324185 (compare the scatter plot), A366804 (rgs-transform).
Cf. also A324103.

Programs

Formula

a(n) = A083254(A163511(n)).
For n > 0, a(n) = A324052(A054429(n)).

A379011 Square array A(n, k) = 2*phi(A246278(n, k)) - A246278(n, k), read by falling antidiagonals; A083254, (2*phi(n)-n), applied to the prime shift array.

Original entry on oeis.org

0, 0, 1, -2, 3, 3, 0, 1, 15, 5, -2, 9, 13, 35, 9, -4, 3, 75, 43, 99, 11, -2, 3, 25, 245, 97, 143, 15, 0, 7, 65, 53, 1089, 163, 255, 17, -6, 27, 31, 301, 133, 1859, 253, 323, 21, -4, 5, 375, 73, 1067, 185, 4335, 355, 483, 27, -2, 9, 91, 1715, 151, 2119, 313, 6137, 565, 783, 29, -8, 9, 125, 473, 11979, 229, 4301, 457, 11109, 781, 899, 35
Offset: 1

Views

Author

Antti Karttunen, Dec 14 2024

Keywords

Comments

Each column is strictly increasing.

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,  -2,    -4,  -2,      0,    -6,    -4,  -2,     -8,
  2 |  1,   3,   1,     9,   3,     3,   7,     27,     5,     9,   9,      9,
  3 |  3,  15,  13,    75,  25,    65,  31,    375,    91,   125,  43,    325,
  4 |  5,  35,  43,   245,  53,   301,  73,   1715,   473,   371,  83,   2107,
  5 |  9,  99,  97,  1089, 133,  1067, 151,  11979,  1261,  1463, 187,  11737,
  6 | 11, 143, 163,  1859, 185,  2119, 229,  24167,  2771,  2405, 295,  27547,
  7 | 15, 255, 253,  4335, 313,  4301, 403,  73695,  4807,  5321, 433,  73117,
  8 | 17, 323, 355,  6137, 457,  6745, 491, 116603,  8165,  8683, 593, 128155,
  9 | 21, 483, 565, 11109, 607, 12995, 733, 255507, 16385, 13961, 817, 298885,
		

Crossrefs

Cf. A040976 (column 1), A378986 (row 1).
Cf. also A378979.

Programs

  • PARI
    up_to = 11325; \\ = binomial(150+1,2)
    A083254(n) = (2*eulerphi(n)-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));
    A379011sq(row,col) = A083254(A246278sq(row,col));
    A379011list(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] = A379011sq(col,(a-(col-1))))); (v); };
    v379011 = A379011list(up_to);
    A379011(n) = v379011[n];

Formula

A(n, k) = 2*A379010(n, k) - A246278(n, k).

A297153 Reversing binary representation of A083254(n), 2*phi(n) - n.

Original entry on oeis.org

1, 0, 1, 0, 7, 6, 13, 0, 7, 6, 25, 12, 31, 6, 1, 0, 19, 10, 49, 12, 7, 6, 61, 24, 19, 6, 25, 12, 47, 18, 37, 0, 11, 6, 21, 20, 103, 6, 25, 24, 107, 54, 121, 12, 7, 6, 117, 48, 103, 30, 21, 12, 87, 54, 41, 24, 19, 6, 73, 36, 79, 6, 25, 0, 35, 46, 193, 12, 55, 58, 205, 40, 203, 6, 13, 12, 127, 34, 213, 48, 47, 6, 241
Offset: 1

Views

Author

Antti Karttunen, Dec 26 2017

Keywords

Crossrefs

Programs

Formula

If A083254(n) > 0, then a(n) = A065621(A083254(n)), otherwise a(n) = A048724(-A083254(n)).
For all n >= 1, A065620(a(n)) = A083254(n)

A297154 Balanced ternary representation of A083254(n), 2*phi(n)-n.

Original entry on oeis.org

1, 0, 1, 0, 3, 7, 17, 0, 3, 7, 9, 8, 14, 7, 1, 0, 51, 21, 47, 8, 3, 7, 48, 19, 51, 7, 9, 8, 27, 67, 32, 0, 16, 7, 13, 24, 38, 7, 9, 19, 39, 63, 161, 8, 3, 7, 153, 68, 38, 20, 13, 8, 141, 63, 34, 19, 51, 7, 138, 56, 152, 7, 9, 0, 31, 55, 149, 8, 46, 71, 105, 57, 101, 7, 17, 8, 160, 60, 89, 68, 27, 7, 81, 72, 160, 7
Offset: 1

Views

Author

Antti Karttunen, Dec 26 2017

Keywords

Crossrefs

Programs

Formula

If A083254(n) >= 0, then a(n) = A117967(A083254(n)), otherwise a(n) = A117968(-A083254(n)).
For all n >= 1, A117966(a(n)) = A083254(n).

A318304 a(n) = A083254(n)/A003557(n) = (2*A173557(n) - A007947(n)).

Original entry on oeis.org

1, 0, 1, 0, 3, -2, 5, 0, 1, -2, 9, -2, 11, -2, 1, 0, 15, -2, 17, -2, 3, -2, 21, -2, 3, -2, 1, -2, 27, -14, 29, 0, 7, -2, 13, -2, 35, -2, 9, -2, 39, -18, 41, -2, 1, -2, 45, -2, 5, -2, 13, -2, 51, -2, 25, -2, 15, -2, 57, -14, 59, -2, 3, 0, 31, -26, 65, -2, 19, -22, 69, -2, 71, -2, 1, -2, 43, -30, 77, -2, 1, -2, 81, -18, 43, -2, 25
Offset: 1

Views

Author

Antti Karttunen, Aug 26 2018

Keywords

Crossrefs

Programs

Formula

a(n) = A083254(n)/A003557(n) = 2*A173557(n) - A007947(n).
a(n) = A173557(n) - A318305(n).
Sum_{k=1..n} a(k) ~ c * n^2 / 2, where c = 2 * A307868 - A065463 = 0.238919... . - Amiram Eldar, Dec 07 2023
Showing 1-10 of 51 results. Next