A108729
Numbers k that divide A076127(k); or k such that A076127(k) is a Niven number.
Original entry on oeis.org
1, 3, 7, 9, 21, 27, 57, 81, 111, 189, 243, 333, 441, 729, 777, 999, 1161, 1701, 2109, 2187, 2529, 2709, 2763, 2793, 2997
Offset: 1
a(2)=3 because A076127(3)=101001 and 101001/3 = 33667.
A076131
a(n) = 2^n*a(n-1) + 1, a(0) = 0.
Original entry on oeis.org
0, 1, 5, 41, 657, 21025, 1345601, 172236929, 44092653825, 22575438758401, 23117249288602625, 47344126543058176001, 193921542320366288900097, 1588605274688440638669594625, 26027708820495411423962638336001, 852875962629993641540407732994080769
Offset: 0
Kyle Hunter (hunterk(AT)raytheon.com), Oct 31 2002
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a[0] = 0; a[n_] := 2^n a[n - 1] + 1; Table[ a[n], {n, 0, 13}]
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a(n)=if(n<0,0,subst(Polrev(Vec(sum(k=1,n,x^(k*(k+1)/2)))),x,2))
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a(n)=if(n<1,0,1+a(n-1)*2^n)
Showing 1-2 of 2 results.
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