A380932 -id:A380932 - cp's OEIS frontend

A381072 Odd terms in A381071.

322245, 590205, 874665, 3378375, 4729725, 6081075, 6818175, 8783775, 8906625, 9889425, 10135125, 13378365, 15049125, 15909075, 16253055, 18922365, 32684085, 34754265, 36916425, 38144925, 38439765, 39471705, 44778825, 46990125, 57506085, 75200265, 84047355, 88852995

Offset: 1

Amiram Eldar, Feb 13 2025

The first 142 terms are all divisible by 3.

The least term that is not divisible by 5 is a(57) = 885593709.

Amiram Eldar, Table of n, a(n) for n = 1..142

Intersection of A005408 and A381071.

Subsequence of A380929 and A380932.

Select[Range[1, 70000, 2], q] (* using the function q[n_] from A381071 *)

A380933 Numbers k such that k and k+1 are both in A380929.

Original entry on oeis.org

121643775, 157390064, 161019495, 275734304, 584899875, 1493214975, 1614323655, 2043708975, 3081783375, 3118599224, 3426851295, 3902652495, 3947893424, 5849043375, 11731509855, 12138531615, 13008843224, 14598032624, 17588484584, 19782621495, 20191564575, 20759209064

Offset: 1

Amiram Eldar, Feb 08 2025

Numbers k such that A380845(k) > 2*k and A380845(k+1) > 2*(k+1).

			121643775 is a term since A380845(121643775) = 244722015 > 2 * 121643775 = 243287550, and A380845(121643776) = 256456081 > 2 * 121643776 = 243287552.

Amiram Eldar, Table of n, a(n) for n = 1..32

Subsequence of A096399 and A380929.
Cf. A380845, A380932.
Similar sequences: A283418, A318167, A327635, A327942, A331412, A333951, A357608, A364727, A364861.

q[k_] := Module[{h = DigitCount[k, 2, 1]}, DivisorSum[k, # &, DigitCount[#, 2, 1] == h &] > 2*k];
seq[lim_] := Module[{s = {}}, Do[If[q[k], If[q[k-1], AppendTo[s, k-1]]; If[q[k+1], AppendTo[s, k]]], {k, 3, lim, 2}]; s];
seq[3*10^8]

isab(k) = {my(h = hammingweight(k)); sumdiv(k, d, d*(hammingweight(d) == h)) > 2*k;}
list(lim) = forstep(k = 3, lim, 2, if(isab(k), if(isab(k-1), print1(k-1, ", ")); if(isab(k+1), print1(k, ", "))));

cp's OEIS Frontend

A381072 Odd terms in A381071.

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