A381582 Numbers k such that k and k+1 are both terms in A381581.
1, 2, 3, 20, 21, 27, 44, 55, 56, 57, 75, 95, 110, 111, 115, 152, 175, 207, 264, 287, 291, 304, 305, 344, 364, 365, 377, 380, 395, 398, 399, 404, 425, 435, 455, 534, 584, 605, 815, 846, 847, 864, 888, 930, 987, 992, 1004, 1011, 1024, 1025, 1064, 1084, 1085, 1145, 1182
Offset: 1
Examples
1 is a term since A291711(1) = 1 divides 1 and A291711(2) = 2 divides 2. 20 is a term since A291711(20) = 4 divides 20 and A291711(21) = 1 divides 21.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Crossrefs
Programs
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Mathematica
f[n_] := f[n] = Fibonacci[2*n]; q[n_] := q[n] = Module[{s = 0, m = n, k}, While[m > 0, k = 1; While[m > f[k], k++]; If[m < f[k], k--]; If[m >= 2*f[k], s += 2; m -= 2*f[k], s++; m -= f[k]]]; Divisible[n, s]]; Select[Range[1200], q[#] && q[#+1] &] -
PARI
mx = 20; fvec = vector(mx, i, fibonacci(2*i)); f(n) = if(n <= mx, fvec[n], fibonacci(2*n)); is1(n) = {my(s = 0, m = n, k); while(m > 0, k = 1; while(m > f(k), k++); if(m < f(k), k--); if(m >= 2*f(k), s += 2; m -= 2*f(k), s++; m -= f(k))); !(n % s);} list(lim) = {my(q1 = is1(1), q2); for(k = 2, lim, q2 = is1(k); if(q1 && q2, print1(k-1, ", ")); q1 = q2);}
Comments