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 34 results. Next

A297114 Möbius transform of A294898, where A294898 is deficiency minus binary weight.

Original entry on oeis.org

0, 0, 0, 0, 2, -2, 3, 0, 3, -2, 7, -4, 9, -2, 0, 0, 14, -6, 15, -4, 4, -2, 18, -8, 14, -2, 7, -4, 24, -14, 25, 0, 9, -2, 14, -12, 33, -2, 9, -8, 37, -18, 38, -4, 3, -2, 41, -16, 35, -10, 12, -4, 48, -18, 24, -8, 15, -2, 53, -28, 55, -2, 6, 0, 33, -26, 63, -4, 21, -22, 66, -24, 69, -2, 6, -4, 44, -30, 73, -16, 28, -2
Offset: 1

Views

Author

Antti Karttunen, Dec 26 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Table[DivisorSum[n, MoebiusMu[n/#] (2 # - DigitCount[2 #, 2, 1] - DivisorSigma[1, #]) &], {n, 82}] (* Michael De Vlieger, Mar 11 2019 *)
  • PARI
    A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
    A297114(n) = sumdiv(n,d,moebius(n/d)*(A005187(d)-sigma(d)));

Formula

a(n) = Sum_{d|n} A008683(n/d)*A294898(d).
a(n) = A297111(n) - n.
a(n) = A297117(n) - A051953(n).
a(n) = A083254(n) - A297115(n).
a(2n) = A083254(2n) = A378986(n) = -2*A176095(n).
a(n) = A294898(n) - A317844(n).

A326130 a(n) = gcd(A000120(n), A294898(n)) = gcd(A000120(n), sigma(n)-A005187(n)).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Jun 09 2019

Keywords

Crossrefs

Programs

Formula

a(n) = gcd(A000120(n), A294898(n)) = gcd(A000120(n), A000203(n)-A005187(n)).

A318311 Filter sequence combining A278222(n) and A294898(n).

Original entry on oeis.org

1, 1, 2, 1, 3, 4, 5, 1, 6, 7, 8, 9, 10, 11, 12, 1, 13, 14, 15, 16, 17, 18, 19, 20, 21, 8, 22, 23, 24, 25, 26, 1, 27, 28, 29, 30, 31, 32, 19, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 1, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 10, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 62, 79
Offset: 1

Views

Author

Antti Karttunen, Aug 25 2018

Keywords

Comments

Restricted growth sequence transform of ordered pair [A278222(n), A294898(n)].
For all i, j: a(i) = a(j) => A318310(i) = A318310(j) => A033879(i) = A033879(j).

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; };
    A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
    A294898(n) = (A005187(n)-sigma(n));
    A318311aux(n) = [A278222(n), A294898(n)]; \\ Needs also code from A286622.
    v318311 = rgs_transform(vector(up_to,n,A318311aux(n)));
    A318311(n) = v318311[n];

A324348 a(n) = A294898(A005940(1+n)), where A294898(k) = A005187(k) - A000203(k).

Original entry on oeis.org

0, 0, 0, 0, 2, -2, 3, 0, 3, 0, 2, -6, 16, -5, 10, 0, 7, 1, 7, -4, 19, -16, 8, -14, 38, 4, 22, -21, 88, -16, 38, 0, 9, 5, 16, -3, 33, -15, 16, -12, 54, -7, 14, -52, 96, -58, 26, -30, 104, 22, 62, -20, 142, -76, 43, -53, 280, 26, 119, -68, 464, -42, 116, 0, 14, 7, 18, 1, 44, -14, 38, -11, 65, -1, 38, -59, 174, -66, 52, -28, 113, 16, 72, -59, 191, -160, 0, -124
Offset: 0

Views

Author

Antti Karttunen, Feb 24 2019

Keywords

Comments

Positions of zeros is given by the sequence A156552(A295296(n)), n >= 1, sorted into ascending order: 0, 1, 2, 3, 7, 9, 15, 31, 63, 86, 127, 255, 511, 519, 1023, 2047, 4095, 8191, 16383, 32767, ...

Crossrefs

Programs

  • PARI
    A324348(n) = { my(m1=2, m2=1, p=2, mp=p*p); while(n, if(!(n%2), p=nextprime(1+p); mp = p*p, m1 *= p; if(3==(n%4), mp *= p, m2 *= (mp-1)/(p-1))); n>>=1); ((m1-m2)-hammingweight(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
    A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
    A294898(n) = (A005187(n) - sigma(n));
    A324348(n) = A294898(A005940(1+n));

Formula

a(n) = A294898(A005940(1+n)).
a(n) = A324055(n) - A000120(A005940(1+n)).

A326131 Positive numbers n for which A000120(n) = k*A294898(n), with k < 0; numbers for which A326130(n) = sigma(n) - A005187(n).

Original entry on oeis.org

6, 28, 110, 496, 884, 8128, 18632, 85936, 116624, 15370304, 33550336, 73995392, 815634435, 3915380170, 5556840416, 6800695312, 8589869056
Offset: 1

Views

Author

Antti Karttunen, Jun 09 2019

Keywords

Comments

No further terms below 2^31.
See also comments in A326133.
The quotients A000120(k)/(sigma(k)-A005187(k)) for these terms are: 1, 1, 5, 1, 3, 1, 5, 9, 2, 2, 1, 2, 2. Ones occur at the positions of perfect numbers.
a(18) > 10^11. - Amiram Eldar, Jan 03 2021

Examples

			110 is "1101110" in binary, thus A000120(110) = 5. Sigma(110) = 216, while A005187(110) = 215, thus as 5 = 5*(216-215), 110 is included in this sequence.
		

Crossrefs

Intersection of A326132 and A326133, also of A326132 and A326138.
Cf. also A325981, A326141.

Programs

  • Mathematica
    q[n_] := Module[{bw = DigitCount[n, 2, 1], ab = DivisorSigma[1, n] - 2*n, sum}, (sum = ab + bw) > 0 && Divisible[bw, sum]]; Select[Range[10^5], q] (* Amiram Eldar, Jan 03 2021 *)
  • PARI
    A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
    isA326131(n) = { my(t=sigma(n)-A005187(n)); (gcd(hammingweight(n), t) == t); };

Extensions

a(14)-a(17) from Amiram Eldar, Jan 03 2021

A317844 Difference between A294898 and its Möbius transform (A297114).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, -2, 0, 3, 2, 0, 0, 1, 0, 0, 3, 7, 0, -6, 2, 9, 3, 1, 0, -2, 0, 0, 7, 14, 5, -9, 0, 15, 9, -4, 0, 3, 0, 5, 5, 18, 0, -14, 3, 14, 14, 7, 0, 2, 9, -3, 15, 24, 0, -24, 0, 25, 10, 0, 11, 12, 0, 12, 18, 15, 0, -29, 0, 33, 16, 13, 10, 14, 0, -12, 10, 37, 0, -23, 16, 38, 24, 1, 0, -16, 12, 16, 25
Offset: 1

Views

Author

Antti Karttunen, Aug 09 2018

Keywords

Crossrefs

Programs

  • PARI
    A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
    A317844(n) = -sumdiv(n,d,(dA005187(d)-sigma(d)));

Formula

a(n) = -Sum_{d|n, dA008683(n/d)*A294898(d).
a(n) = A294898(n) - A297114(n).
a(n) = A300244(n) - A001065(n).

A323167 a(n) = A294898(A122111(n)).

Original entry on oeis.org

0, 0, 0, 0, 0, -2, 0, 2, 3, -6, 0, 0, 0, -14, -5, 3, 0, 2, 0, -4, -21, -30, 0, 1, 10, -62, 16, -12, 0, -16, 0, 7, -53, -126, -16, 7, 0, -254, -117, -3, 0, -52, 0, -28, 4, -510, 0, 5, 38, 8, -245, -60, 0, 19, -68, -11, -501, -1022, 0, -15, 0, -2046, -20, 9, -172, -124, 0, -124, -1013, -58, 0, 16, 0, -4094, 22, -252, -42, -268, 0, 1, 38
Offset: 1

Views

Author

Antti Karttunen, Jan 10 2019

Keywords

Crossrefs

Programs

Formula

a(n) = A294898(A122111(n)).
a(n) = A323174(n) - A322867(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];

A318447 a(n) = Sum_{d|n, dA294898(d), where A294898(d) = A005187(d) - sigma(d).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, -2, 0, 3, 2, 0, 0, 1, 0, 2, 3, 7, 0, -8, 2, 9, 3, 4, 0, 2, 0, 0, 7, 14, 5, -10, 0, 15, 9, -2, 0, 9, 0, 12, 7, 18, 0, -22, 3, 18, 14, 16, 0, 6, 9, 1, 15, 24, 0, -24, 0, 25, 13, 0, 11, 26, 0, 26, 18, 25, 0, -45, 0, 33, 20, 28, 10, 32, 0, -14, 13, 37, 0, -15, 16, 38, 24, 13, 0, -8, 12, 34, 25, 41, 17, -52, 0
Offset: 1

Views

Author

Antti Karttunen, Aug 27 2018

Keywords

Crossrefs

Programs

Formula

a(n) = Sum_{d|n, dA294898(d).
a(n) = A318448(n) - A294898(n).
a(n) = A318445(n) - A211779(n).
a(n) = A296074(n) - A292257(n).

A318448 a(n) = Sum_{d|n} A294898(d), where A294898(d) = A005187(d) - sigma(d).

Original entry on oeis.org

0, 0, 0, 0, 2, -2, 3, 0, 3, 2, 7, -8, 9, 4, 4, 0, 14, -4, 15, -2, 10, 12, 18, -22, 18, 16, 13, 1, 24, -14, 25, 0, 23, 26, 24, -31, 33, 28, 27, -14, 37, -6, 38, 13, 15, 34, 41, -52, 41, 22, 40, 19, 48, -10, 42, -10, 45, 46, 53, -76, 55, 48, 29, 0, 55, 12, 63, 34, 57, 18, 66, -98, 69, 64, 42, 37, 64, 16, 73, -42, 51, 72, 78, -74, 74, 74, 73, 6
Offset: 1

Views

Author

Antti Karttunen, Aug 27 2018

Keywords

Comments

Inverse Möbius transform of A294898.

Crossrefs

Programs

Formula

a(n) = Sum_{d|n} A294898(d).
a(n) = A318447(n) + A294898(n).
a(n) = A318446(n) - A007429(n).
a(n) = A296075(n) - A093653(n).
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