A323174 -id:A323174 - cp's OEIS frontend

A323168 Lexicographically earliest sequence such that for all i, j, a(i) = a(j) => f(i) = f(j), where f(n) = [A322867(n), A323174(n)] for n > 1, and f(1) = 0.

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

Offset: 1

Antti Karttunen, Jan 10 2019

nonn

Restricted growth sequence transform of function f, with f(1) = 0 and f(n) = [A322867(n), A323174(n)] for n > 1.
Equally, restricted growth sequence transform of function f, with f(1) = 0 and f(n) = A318310(A122111(n)) for n > 1.
For all i, j:
  a(i) = a(j) => A322867(i) = A322867(j),
  a(i) = a(j) => A323167(i) = A323167(j),
  a(i) = a(j) => A323174(i) = A323174(j).

Cf. A000203, A005187, A122111, A294898, A318310, A322867, A323167, A323173, A323174.

Cf. also A323240.

up_to = 4096;
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; };
A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
A294898(n) = (A005187(n)-sigma(n));
A318310aux(n) = [hammingweight(n), A294898(n)];
A323168aux(n) = if(1==n,0,A318310aux(A122111(n)));
v323168 = rgs_transform(vector(up_to, n, A323168aux(n)));
A323168(n) = v323168[n];

A033879 Deficiency of n, or 2n - (sum of divisors of n).

Original entry on oeis.org

1, 1, 2, 1, 4, 0, 6, 1, 5, 2, 10, -4, 12, 4, 6, 1, 16, -3, 18, -2, 10, 8, 22, -12, 19, 10, 14, 0, 28, -12, 30, 1, 18, 14, 22, -19, 36, 16, 22, -10, 40, -12, 42, 4, 12, 20, 46, -28, 41, 7, 30, 6, 52, -12, 38, -8, 34, 26, 58, -48, 60, 28, 22, 1, 46, -12, 66, 10, 42, -4, 70, -51

Offset: 1

N. J. A. Sloane

Records for the sequence of the absolute values are in A075728 and the indices of these records in A074918. - R. J. Mathar, Mar 02 2007
a(n) = 1 iff n is a power of 2. a(n) = n - 1 iff n is prime. - Omar E. Pol, Jan 30 2014
If a(n) = 1 then n is called a least deficient number or an almost perfect number. All the powers of 2 are least deficient numbers but it is not known if there exists a least deficient number that is not a power of 2. See A000079. - Jianing Song, Oct 13 2019
It is not known whether there are any -1's in this sequence. See comment in A033880. - Antti Karttunen, Feb 02 2020

			For n = 10 the divisors of 10 are 1, 2, 5, 10, so the deficiency of 10 is 10 minus the sum of its proper divisors or simply 10 - 5 - 2 - 1 = 2. - _Omar E. Pol_, Dec 27 2013

Richard K. Guy, Unsolved Problems in Number Theory, 3rd Edition, Springer, 2004, Section B2, pp. 74-84.
James J. Tattersall, Elementary Number Theory in Nine Chapters, Cambridge University Press, 1999, page 147.

N. J. A. Sloane, Table of n, a(n) for n = 1..25000 [First 2000 terms from T. D. Noe, terms up to 16384 from Antti Karttunen]
Nichole Davis, Dominic Klyve and Nicole Kraght, On the difference between an integer and the sum of its proper divisors, Involve, Vol. 6 (2013), No. 4, 493-504; DOI: 10.2140/involve.2013.6.493.
Jose A. B. Dris, Conditions Equivalent to the Descartes-Frenicle-Sorli Conjecture on Odd Perfect Numbers, arXiv preprint arXiv:1610.01868 [math.NT], 2016.
Jose Arnaldo B. Dris, Analysis of the Ratio D(n)/n, arXiv:1703.09077 [math.NT], 2017.
Jose Arnaldo Bebita Dris, On a curious biconditional involving the divisors of odd perfect numbers, Notes on Number Theory and Discrete Mathematics, 23(4) (2017), 1-13.
Jose Arnaldo Bebita Dris and Immanuel Tobias San Diego, Some Modular Considerations Regarding Odd Perfect Numbers, arXiv:2002.12139 [math.NT], 2020.
Jose Arnaldo Bebita Dris and Doli-Jane Uvales Tejada, Conditions equivalent to the Descartes-Frenicle-Sorli Conjecture on odd perfect numbers - Part II, Notes on Number Theory and Discrete Mathematics (2018) Vol. 24, No. 3, 62-67.
Jose Arnaldo Bebita Dris and Doli-Jane Uvales Tejada, A note on the OEIS sequence A228059, Notes on Number Theory and Discrete Mathematics (2019) Vol. 25, No. 1, 199-205.
Index entries for sequences related to sigma(n).

Cf. A000396 (positions of zeros), A005100 (of positive terms), A005101 (of negative terms).
Cf. A000203, A033880, A074918, A075728, A192895, A286385, A286449, A295881, A295882.
Cf. A083254 (Möbius transform), A228058, A296074, A296075, A323910, A325636, A325826, A325970, A325976.
Cf. A141545 (positions of a(n) = -12).
For this sequence applied to various permutations of natural numbers and some other sequences, see A323174, A323244, A324055, A324185, A324546, A324574, A324575, A324654, A325379.

with(numtheory): A033879:=n->2*n-sigma(n): seq(A033879(n), n=1..100);

Table[2n-DivisorSigma[1,n],{n,80}] (* Harvey P. Dale, Oct 24 2011 *)

a(n)=2*n-sigma(n) \\ Charles R Greathouse IV, Oct 13 2016

from sympy import divisor_sigma
def A033879(n): return (n<<1)-divisor_sigma(n) # Chai Wah Wu, Apr 13 2024

[2*n-sigma(n, 1) for n in range(1, 73)] # Stefano Spezia, Jul 18 2025

a(n) = -A033880(n).
a(n) = A005843(n) - A000203(n). - Omar E. Pol, Dec 14 2008
a(n) = n - A001065(n). - Omar E. Pol, Dec 27 2013
G.f.: 2*x/(1 - x)^2 - Sum_{k>=1} k*x^k/(1 - x^k). - Ilya Gutkovskiy, Jan 24 2017
a(n) = A286385(n) - A252748(n). - Antti Karttunen, May 13 2017
From Antti Karttunen, Dec 29 2017: (Start)
a(n) = Sum_{d|n} A083254(d).
a(n) = Sum_{d|n} A008683(n/d)*A296075(d).
a(n) = A065620(A295881(n)) = A117966(A295882(n)).
a(n) = A294898(n) + A000120(n).
(End)
From Antti Karttunen, Jun 03 2019: (Start)
Sequence can be represented in arbitrarily many ways as a difference of the form (n - f(n)) - (g(n) - n), where f and g are any two sequences whose sum f(n)+g(n) = sigma(n). Here are few examples:
a(n) = A325314(n) - A325313(n) = A325814(n) - A034460(n) = A325978(n) - A325977(n).
a(n) = A325976(n) - A325826(n) = A325959(n) - A325969(n) = A003958(n) - A324044(n).
a(n) = A326049(n) - A326050(n) = A326055(n) - A326054(n) = A326044(n) - A326045(n).
a(n) = A326058(n) - A326059(n) = A326068(n) - A326067(n).
a(n) = A326128(n) - A326127(n) = A066503(n) - A326143(n).
a(n) = A318878(n) - A318879(n).
a(A228058(n)) = A325379(n). (End)
Sum_{k=1..n} a(k) ~ c * n^2, where c = 1 - Pi^2/12 = 0.177532... . - Amiram Eldar, Dec 07 2023

Definition corrected by N. J. A. Sloane, Jul 04 2005

A323244 a(1) = 0; and for n > 1, a(n) = A033879(A156552(n)).

Original entry on oeis.org

0, 1, 1, 2, 1, 4, 1, 6, 0, 5, 1, 10, 1, 16, 2, 6, 1, 12, 1, 18, -3, 18, 1, 22, -4, 46, 4, 22, 1, 10, 1, 30, 14, 82, -2, 14, 1, 256, -12, 22, 1, 36, 1, 66, 8, 226, 1, 46, -12, 19, 8, 130, 1, 28, -19, 70, -12, 748, 1, 42, 1, 1362, 16, 22, 10, 42, 1, 214, 254, 40, 1, 38, 1, 3838, 10, 406, -10, 106, 1, 78, -12, 5458, 1, 26, -72, 12250, -348, 30, 1, 12

Offset: 1

Antti Karttunen, Jan 10 2019

sign

After a(1) = 0, the other zeros occur for k >= 1, at A005940(1+A000396(k)), which, provided no odd perfect numbers exist, is equal to A324201(k) = A062457(A000043(k)): 9, 125, 161051, 410338673, ..., etc.

There are 2321 negative terms among the first 10000 terms.

Antti Karttunen, Table of n, a(n) for n = 1..10000 (based on Hans Havermann's factorization of A156552)
Index entries for sequences related to binary expansion of n
Index entries for sequences computed from indices in prime factorization
Index entries for sequences related to sigma(n)

Cf. A000043, A000396, A033879, A064989, A156552, A297112, A323240, A323243, A323245, A323248, A324115, A324051, A324103, A324396, A324398, A324543, A324713.
Cf. A324201 (positions of zeros, conjectured), A324551 (of negative terms), A324720 (of nonnegative terms), A324721 (of positive terms), A324731, A324732.
Cf. A329644 (Möbius transform).
Cf. A323174, A324055, A324185, A324546 for other permutations of deficiency, and also A324574, A324575, A324654.

Array[2 # - If[# == 0, 0, DivisorSigma[1, #]] &@ Floor@ Total@ Flatten@ MapIndexed[#1 2^(#2 - 1) &, Flatten[Table[2^(PrimePi@ #1 - 1), {#2}] & @@@ FactorInteger@ #]] &, 90] (* Michael De Vlieger, Apr 21 2019 *)

A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
A156552(n) = if(1==n, 0, if(!(n%2), 1+(2*A156552(n/2)), 2*A156552(A064989(n))));
A323244(n) = if(1==n, 0, my(k=A156552(n)); (2*k)-sigma(k));

from sympy import divisor_sigma, primepi, factorint
def A323244(n): return (lambda n: (n<<1)-divisor_sigma(n))(sum((1< 1 else 0 # Chai Wah Wu, Mar 10 2023

a(n) = 2*A156552(n) - A323243(n).
a(1) = 0; and for n > 1, a(n) = A033879(A156552(n)).
a(n) = A323248(n) + A001222(n) = (A323247(n) - A323243(n)) + A001222(n).
From Antti Karttunen, Mar 12 2019 & Nov 23 2019: (Start)
a(n) = Sum_{d|n} (2*A297112(d) - A324543(d)) = Sum_{d|n} A329644(d).
A002487(a(n)) = A324115(n).
a(n) = A329638(n) - A329639(n).
a(n) = A329645(n) - A329646(n).
(End)

A324055 Deficiency of Doudna-sequence: a(n) = A033879(A005940(1+n)).

Original entry on oeis.org

1, 1, 2, 1, 4, 0, 5, 1, 6, 2, 6, -4, 19, -3, 14, 1, 10, 4, 10, -2, 22, -12, 12, -12, 41, 7, 26, -19, 94, -12, 41, 1, 12, 8, 18, 0, 38, -12, 22, -10, 58, -4, 18, -48, 102, -54, 30, -28, 109, 25, 66, -17, 148, -72, 47, -51, 286, 32, 126, -64, 469, -39, 122, 1, 16, 10, 22, 4, 46, -12, 42, -8, 70, 4, 42, -56, 178, -60, 58, -26, 118, 20

Offset: 0

Antti Karttunen, Feb 14 2019

Both here and in the mirror image sequence A324185, the lowermost (asinh) scatter plot shows on the y = 0 line the numbers that correspond to the perfect numbers. Compare also to the scatter plot of A243492.

Antti Karttunen, Table of n, a(n) for n = 0..8192
Antti Karttunen, Data supplement: n, a(n) computed for n = 0..70327
Index entries for sequences related to binary expansion of n
Index entries for sequences related to sigma(n)

Cf. A000120, A033879, A054429.
See A106737, A290077, A323915, A324052, A324054, A324056, A324057, A324058, A324114, A324335, A324340, A324348, A324349, A324394, A324395 for other sequences as permuted by A005940, and compare their scatter plots.
Cf. also A243492, A323174, A323244, A324185, A324346, A324347, A324654.

Array[Block[{p = Partition[Split[Join[IntegerDigits[#, 2], {2}]], 2]}, 2 # - DivisorSigma[1, #] &[Times @@ Flatten@ Table[Prime[Count[Flatten@ #, 0] + 1]^#[[1, 1]] &@ Take[p, -i], {i, Length[p]}]]] &, 82, 0] (* Michael De Vlieger, Mar 11 2019, after Robert G. Wilson v at A005940 *)

A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t }; \\ From A005940
A033879(n) = (2*n-sigma(n));
A324055(n) = A033879(A005940(1+n));

A324055(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); };

a(n) = A033879(A005940(1+n)).
a(n) = 2*A005940(1+n) - A324054(n).
For n > 0, a(n) = A324185(A054429(n)).
a(n) = A324348(n) + A000120(A005940(1+n)).

A323173 Sum of divisors computed for conjugated prime factorization: a(n) = A000203(A122111(n)).

Original entry on oeis.org

1, 3, 7, 4, 15, 12, 31, 6, 13, 28, 63, 18, 127, 60, 39, 8, 255, 24, 511, 42, 91, 124, 1023, 24, 40, 252, 31, 90, 2047, 72, 4095, 12, 195, 508, 120, 32, 8191, 1020, 403, 56, 16383, 168, 32767, 186, 93, 2044, 65535, 36, 121, 78, 819, 378, 131071, 48, 280, 120, 1651, 4092, 262143, 96, 524287, 8188, 217, 14, 600, 360, 1048575, 762, 3315, 234

Offset: 1

Antti Karttunen, Jan 10 2019

nonn

Cf. A000203, A038712, A122111, A322819, A323174.

Cf. also A323243.

A122111[n_] := Product[Prime[Sum[If[j < i, 0, 1], {j, #}]], {i, Max[#]}]&[ Flatten[Table[Table[PrimePi[f[[1]]], {f[[2]]}], {f, FactorInteger[n]}]]];
a[n_] := With[{k = A122111[n]}, DivisorSigma[1, k]];
Array[a, 70] (* Jean-François Alcover, Sep 23 2020 *)

A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
A323173(n) = sigma(A122111(n));

a(n) = A000203(A122111(n)).
a(n) = 2*A122111(n) - A323174(n).
a(n) = A322819(n) * A038712(A122111(n)).

A324546 An analog of deficiency (A033879) for nonstandard factorization based on the sieve of Eratosthenes (A083221).

Original entry on oeis.org

1, 1, 2, 1, 4, 0, 6, 1, 5, 2, 10, -4, 12, 4, 6, 1, 16, -3, 18, -2, 14, 8, 22, -12, 19, 10, 10, 0, 28, -12, 30, 1, 12, 14, 22, -19, 36, 16, 18, -10, 40, -12, 42, 4, 41, 20, 46, -28, 41, 7, 26, 6, 52, -12, 94, -8, 22, 26, 58, -48, 60, 28, 22, 1, 38, -54, 66, 10, 30, -4, 70, -51, 72, 34, 30, 12, 58, -12, 78, -26, 42, 38, 82, -64, 102, 40, 18, -4, 88

Offset: 1

Antti Karttunen, Mar 06 2019

sign

Even positions for zeros is given by the even terms of A000396, because they are among the fixed points of permutation A250246. Whether there are any zeros in odd positions depends on whether there are any odd perfect numbers. If such zeros exist, they would not necessarily be in the same positions as in A033879.

Antti Karttunen, Table of n, a(n) for n = 1..16384
Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65539
Index entries for sequences generated by sieves
Index entries for sequences related to sigma(n)

Cf. A000396, A033879, A083221, A250246, A324535, A324545.

Cf. also A323244, A323174, A324574, A324575.

up_to = 65539;
ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om,invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om,invec[i],(1+pt))); outvec; };
A020639(n) = if(n>1, if(n>n=factor(n, 0)[1, 1], n, factor(n)[1, 1]), 1); \\ From A020639
A055396(n) = if(1==n,0,primepi(A020639(n)));
v078898 = ordinal_transform(vector(up_to,n,A020639(n)));
A078898(n) = v078898[n];
A003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); \\ From A003961
A250246(n) = if(1==n,n,my(k = 2*A250246(A078898(n)), r = A055396(n)); if(1==r, k, while(r>1, k = A003961(k); r--); (k)));
A324546(n) = { my(k=A250246(n)); (k+k - sigma(k)); };

a(n) = A033879(A250246(n)) = 2*A250246(n) - A324545(n).

a(n) = A250246(n) - A324535(n).

A324574 a(1) = 0; for n > 1, a(n) = A033879(A087207(n)).

Original entry on oeis.org

0, 1, 1, 1, 1, 2, 1, 1, 1, 4, 1, 2, 1, 5, 0, 1, 1, 2, 1, 4, 2, 16, 1, 2, 1, 18, 1, 5, 1, 6, 1, 1, -3, 46, -4, 2, 1, 82, 14, 4, 1, 10, 1, 16, 0, 256, 1, 2, 1, 4, -12, 18, 1, 2, -2, 5, 8, 226, 1, 6, 1, 748, 2, 1, -19, 18, 1, 46, -12, 12, 1, 2, 1, 1362, 0, 82, -12, 22, 1, 4, 1, 3838, 1, 10, 10, 5458, 254, 16, 1, 6, -10, 256, -348, 12250

Offset: 1

Antti Karttunen, Mar 08 2019

sign

As A087207 is a surjective function that toggles the parity, it follows that if it can be proved/disproved that a(n) = 0 for some/any even n, then it also proves/disproves the existence of odd perfect numbers.

The positions (n > 1) of zeros in squarefree n, 15, 385, ..., can be obtained as A019565(A000396(n)).

Cf. A000396, A007947, A033879, A019565, A087207, A324573, A324575.

Cf. also A323244, A323174, A324546.

A033879(n) = (2*n-sigma(n));
A087207(n) = vecsum(apply(p->1<A087207
A324574(n) = if(1==n,0,A033879(A087207(n)));

a(1) = 0; for n > 1, a(n) = A033879(A087207(n)).

a(n) = a(A007947(n)) = A324575(A007947(n)).

A324575 a(1) = 0; for n > 1, a(n) = A033879(A048675(n)).

Original entry on oeis.org

0, 1, 1, 1, 1, 2, 1, 2, 1, 4, 1, 1, 1, 5, 0, 1, 1, 4, 1, 0, 2, 16, 1, 4, 1, 18, 0, 2, 1, 6, 1, 4, -3, 46, -4, 0, 1, 82, 14, 6, 1, 10, 1, -3, 1, 256, 1, 0, 1, 5, -12, 14, 1, 6, -2, 10, 8, 226, 1, 1, 1, 748, -4, 0, -19, 18, 1, -12, -12, 12, 1, 6, 1, 1362, 2, 8, -12, 22, 1, 1, 1, 3838, 1, -4, 10, 5458, 254, 18, 1, 5, -10, -12, -348, 12250

Offset: 1

Antti Karttunen, Mar 07 2019

sign

Cf. A007947, A033879, A048675, A324573, A324574.

Cf. also A323244, A323174, A324546.

A033879(n) = (2*n-sigma(n));
A048675(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2; };
A324575(n) = if(1==n,0,A033879(A048675(n)));

a(1) = 0; for n > 1, a(n) = A033879(A048675(n)).
a(n) = 2*A048675(n) - A324573(n).
a(A007947(n)) = A324574(n).
a(p) = 1 for all primes p.

A323903 a(n) = A002487(A122111(n)).

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 3, 4, 2, 1, 3, 1, 2, 4, 3, 1, 4, 1, 3, 4, 2, 1, 3, 8, 2, 7, 3, 1, 4, 1, 5, 4, 2, 8, 8, 1, 2, 4, 3, 1, 4, 1, 3, 7, 2, 1, 5, 14, 12, 4, 3, 1, 9, 8, 3, 4, 2, 1, 8, 1, 2, 7, 5, 8, 4, 1, 3, 4, 12, 1, 6, 1, 2, 18, 3, 14, 4, 1, 5, 9, 2, 1, 8, 8, 2, 4, 3, 1, 9, 14, 3, 4, 2, 8, 5, 1, 16, 7, 6, 1, 4, 1, 3, 18

Offset: 1

Antti Karttunen, Feb 09 2019

nonn

Antti Karttunen, Table of n, a(n) for n = 1..16384
Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537
Index entries for sequences computed from indices in prime factorization
Index entries for sequences related to Stern's sequences

Cf. A002487, A122111, A322865.

Cf. also A323168, A323174, A323902.

A002487(n) = { my(a=1, b=0); while(n>0, if(bitand(n, 1), b+=a, a+=b); n>>=1); (b); }; \\ From A002487
A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
A323903(n) = A002487(A122111(n));

a(n) = A002487(A122111(n)) = A002487(A322865(n)).

a(p) = 1 for all primes p.

A324654 a(n) = A033879(A276086(n)).

Original entry on oeis.org

1, 1, 2, 0, 5, -3, 4, 2, 6, -12, 12, -54, 19, 7, 26, -72, 47, -309, 94, 32, 126, -372, 222, -1584, 469, 157, 626, -1872, 1097, -7959, 6, 4, 10, -12, 22, -60, 22, -4, 18, -156, 6, -612, 102, -44, 58, -876, -74, -3372, 502, -244, 258, -4476, -474, -17172, 2502, -1244, 1258, -22476, -2474, -86172, 41, 25, 66, -96, 141, -459, 148, -46, 102

Offset: 0

Antti Karttunen, Mar 10 2019

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Interestingly, this kind of sampling of deficiency (A033879; recall that the range of A276086 does not cover the whole N) biases it strongly towards negative values: of the first 2310 terms, 1565 are negative (~ 68%) and of the first 30030 terms, 22507 are negative (~ 75%). Compare also to A323174, which covers whole N.

Cf. A033879, A276086, A324653.

Cf. also A323174, A324055.

A276086(n) = { my(i=0,m=1,pr=1,nextpr); while((n>0),i=i+1; nextpr = prime(i)*pr; if((n%nextpr),m*=(prime(i)^((n%nextpr)/pr));n-=(n%nextpr));pr=nextpr); m; };
A033879(n) = (2*n-sigma(n));
A324654(n) = A033879(A276086(n));

a(n) = A033879(A276086(n)).

a(n) = 2*A276086(n) - A324653(n).

cp's OEIS Frontend

A323168 Lexicographically earliest sequence such that for all i, j, a(i) = a(j) => f(i) = f(j), where f(n) = [A322867(n), A323174(n)] for n > 1, and f(1) = 0.

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A033879 Deficiency of n, or 2n - (sum of divisors of n).

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A323244 a(1) = 0; and for n > 1, a(n) = A033879(A156552(n)).

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A324055 Deficiency of Doudna-sequence: a(n) = A033879(A005940(1+n)).

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A323173 Sum of divisors computed for conjugated prime factorization: a(n) = A000203(A122111(n)).

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A324546 An analog of deficiency (A033879) for nonstandard factorization based on the sieve of Eratosthenes (A083221).

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A324574 a(1) = 0; for n > 1, a(n) = A033879(A087207(n)).

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