A316096 Numbers m such that A(m+1) = A(m) + 4, where A() = A005101() are the abundant numbers.
3, 6, 11, 13, 17, 18, 21, 24, 25, 32, 35, 40, 43, 46, 47, 50, 53, 60, 63, 64, 69, 72, 75, 78, 85, 88, 91, 94, 95, 100, 105, 106, 109, 112, 115, 117, 121, 124, 127, 130, 132, 136, 139, 140, 147, 148, 151, 154, 157, 159, 165, 168, 171, 176, 177, 180, 181, 184
Offset: 1
Keywords
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Crossrefs
Programs
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GAP
A:=Filtered([1..1000],n->Sigma(n)>2*n);; a:=Filtered([1..Length(A)-1],i->A[i+1]=A[i]+4);
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Maple
with(numtheory): A:=select(n->sigma(n)>2*n,[$1..1000]): a:=select(j->A[j+1]=A[j]+4,[$1..nops(A)-1]);
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Mathematica
Position[Map[{#1, #2 - 4} & @@ # &, Partition[Select[Range[10^3], DivisorSigma[1, #] > 2 # &], 2, 1]], ?(SameQ @@ # &)][[All, 1]] (* _Michael De Vlieger, Jun 29 2018 *) -
PARI
list(lim) = {my(k = 1, k2, m = 0); for(k2 = 2, lim, if(sigma(k2, -1) > 2, if(k2 == k1 + 4, print1(m, ", ")); m++; k1 = k2));} \\ Amiram Eldar, Mar 01 2025
Comments