A379915 -id:A379915 - cp's OEIS frontend

A379917 a(n) is the deficiency of A046390(n), divided by 2.

3, 21, 57, 75, 129, 111, 213, 315, 165, 255, 183, 291, 345, 339, 237, 471, 273, 549, 453, 291, 609, 465, 525, 327, 973, 507, 707, 705, 381, 615, 681, 669, 633, 435, 903, 453, 1361, 795, 939, 717, 1023, 507, 759, 1017, 831, 1245, 1555, 915, 543, 561, 1687, 843, 993

Offset: 1

Hugo Pfoertner, Jan 06 2025

Hugo Pfoertner, Table of n, a(n) for n = 1..10000
Michael De Vlieger, Log log scatterplot of a(n), n = 1..177395.

Cf. A000203, A033879, A046390, A378717, A379915, A379916.

Map[(2 # - DivisorSigma[1, #])/2 &, Select[Range[1, 8001, 2], PrimeNu[#] == PrimeOmega[#] == 4 &] ] (* Michael De Vlieger, Jan 09 2025, after Harvey P. Dale at A046390 *)

a379915_17(limit,np=2) = forstep(k=15, limit, 2, my(f=factor(k)); if(omega(f)==np && bigomega(f)==np, print1((2*k-sigma(f))/2,", ")));
a379915_17(8000,4)

a(n) = (2*A046390(n) - sigma(A046390(n)))/2, where sigma is A000203.

a(n) = A033879(A046390(n))/2.

A379916 a(n) is the deficiency of A046389(n), divided by 2.

Original entry on oeis.org

9, 21, 27, 39, 39, 49, 45, 57, 69, 97, 79, 93, 75, 119, 81, 99, 99, 129, 163, 129, 111, 147, 117, 139, 159, 185, 129, 211, 181, 183, 169, 147, 229, 189, 165, 225, 199, 171, 287, 237, 249, 219, 329, 189, 295, 255, 325, 201, 317, 207, 349, 249, 291, 309, 225, 313

Offset: 1

Hugo Pfoertner, Jan 06 2025

nonn

Hugo Pfoertner, Table of n, a(n) for n = 1..10000

Cf. A000203, A033879, A046389, A379915, A379917.

\\ uses function a379915_17 from A379917
a379915_17(1210,3)

a(n) = (2*A046389(n) - sigma(A046389(n)))/2, where sigma is A000203.

a(n) = A033879(A046389(n))/2.

cp's OEIS Frontend

A379917 a(n) is the deficiency of A046390(n), divided by 2.

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