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 A373094 a(n) is the least number k such that A373092(k) = n. 1
 1, 4, 7, 12, 24, 120, 1260, 1829520 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS a(n) is the least number k such that the number of iterations of the map x -> A093653(x) required to reach from k to a fixed point is n. a(8) > 4*10^10. LINKS Table of n, a(n) for n=0..7. EXAMPLE The iterations for the n = 0..7 are: n a(n) iterations - ------- -------------------------------------------------- 0 1 1 1 4 4 -> 3 2 7 7 -> 4 -> 3 3 12 12 -> 9 -> 5 ->3 4 24 24 -> 12 -> 9 -> 5 -> 3 5 120 120 -> 36 -> 15 -> 9 -> 5 -> 3 6 1260 1260 -> 120 -> 36 -> 15 -> 9 -> 5 -> 3 7 1829520 1829520 -> 1260 -> 120 -> 36 -> 15 -> 9 -> 5 -> 3 MATHEMATICA d[n_] := d[n] = DivisorSum[n, Plus @@ IntegerDigits[#, 2] &]; f[n_] := -2 + Length@ FixedPointList[d, n]; seq[len_] := Module[{s = Table[0, {len}], c = 0, i, n = 1}, While[c < len, i = f[n] + 1; If[i <= len && s[[i]] == 0, c++; s[[i]] = n]; n++]; s]; seq[7] PROG (PARI) f(n) = {my(c = 0); while(6 % n, n = sumdiv(n, d, hammingweight(d)); c++); c; } lista(len) = {my(s = vector(len), c = 0, i, n = 1); while(c < len, i = f(n) + 1; if(i <= len && s[i] == 0, c++; s[i] = n); n++); s; } CROSSREFS Cf. A093653, A095347 (decimal analog), A373092. Sequence in context: A243860 A322619 A299900 * A215329 A208724 A183336 Adjacent sequences: A373091 A373092 A373093 * A373095 A373096 A373098 KEYWORD nonn,base,hard,more AUTHOR Amiram Eldar, May 23 2024 STATUS approved

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Last modified July 24 21:32 EDT 2024. Contains 374585 sequences. (Running on oeis4.)