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A255880 a(n) = n-th Rhonda number to base b = n-th composite number, cf. A002808. 4
10206, 1029, 6622, 44360, 5439, 4888, 58404, 20079, 26296, 36549, 52059, 61376, 131427, 29106, 165504, 137007, 63525, 61115, 22784, 135705, 658896, 563159, 208369, 115506, 1078784, 228436, 152308, 185571, 539213, 152532, 2289001, 193963, 2499742, 298768 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
See A099542 for definition of Rhonda numbers and for more links.
LINKS
Eric Weisstein's World of Mathematics, Rhonda Number
EXAMPLE
Diagonalization of Rhonda numbers to base b = A002808(n), n = 1 .. 8:
. b | n\n 1 2 3 4 5 6 7 8
. ----+---+---------------------------------------------------------------
. 4 | 1 | A100968 [10206] 11935 12150 16031 45030 94185 113022 114415
. 6 | 2 | A100969 855 [1029] 3813 5577 7040 7304 15104 19136
. 8 | 3 | A100970 1836 6318 [6622] 10530 14500 14739 17655 18550
. 9 | 4 | A100973 15540 21054 25331 [44360] 44660 44733 47652 50560
. 10 | 5 | A099542 1568 2835 4752 5265 [5439] 5664 5824 5832
. 12 | 6 | A100971 560 800 3993 4425 4602 [4888] 7315 8296
. 14 | 7 | A100972 11475 18655 20565 29631 31725 45387 [58404] 58667
. 15 | 8 | A100974 2392 2472 11468 15873 17424 18126 19152 [20079]
MATHEMATICA
nc = 34; (* number of composite bases *)
compos = Select[Range[FindRoot[n == nc + PrimePi[n] + 1, {n, nc, 2nc}][[1, 2]] // Floor], CompositeQ];
RhondaQ[n_, b_] := Times @@ IntegerDigits[n, b] == b Total[Times @@@ FactorInteger[n]];
a[n_] := a[n] = Module[{b = compos[[n]], cnt = 0, k}, For[k = 1, True, k++, If[RhondaQ[k, b], cnt++; If[cnt == n, Return[k]]]]];
Table[Print[n, " ", a[n]]; a[n], {n, 1, nc}] (* Jean-François Alcover, Nov 15 2021 *)
PROG
(Haskell)
a255880 n = (filter (rhonda b) $ iterate zeroless 1) !! (n - 1) where
-- function rhonda as defined in A099542
zeroless x = 1 + if r < b - 1 then x else b * zeroless x'
where (x', r) = divMod x b
b = a002808 n
CROSSREFS
Main diagonal of A291925.
Sequence in context: A258890 A255872 A291925 * A100968 A203056 A252330
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Mar 10 2015
STATUS
approved

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Last modified February 23 01:12 EST 2024. Contains 370265 sequences. (Running on oeis4.)