This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
import Data.List (delete)
a095258 n = a095258_list !! (n-1)
a095258_list = 1 : f [2..] 1 where
f xs z = g xs where
g (y:ys) = if mod z' y > 0 then g ys else y : f (delete y xs) (z + y)
z' = z + 2
-- Reinhard Zumkeller, Dec 31 2014
c[] = 0; j = c[1] = 1; s = 3; {j}~Join~Reap[Do[d = Divisors[s]; k = 1; While[c[d[[k]]] > 0, k++]; Set[k, d[[k]]]; Set[c[k], i]; Sow[k]; j = k; s += k, {i, 2, 80}]][[-1, -1]] (* _Michael De Vlieger, Jan 23 2022 *)
from itertools import islice from sympy import divisors def A095258_gen(): # generator of terms bset, s = {1}, 3 yield 1 while True: for d in divisors(s): if d not in bset: yield d bset.add(d) s += d break A095258_list = list(islice(A095258_gen(),30)) # Chai Wah Wu, Jan 25 2022
import Data.List (delete)
a253415 n = a253415_list !! (n-2)
a253415_list = f [2..] 1 where
f xs z = g xs where
g (y:ys) = if mod z' y > 0 then g ys else x : f xs' (z + y)
where xs'@(x:_) = delete y xs
z' = z + 2
-- Reinhard Zumkeller, Dec 31 2014
c[] = 0; c[1] = j = 1; u = 2; s = 3; Reap[Do[d = Divisors[s]; k = 1; While[c[d[[k]]] > 0, k++]; Set[k, d[[k]]]; Set[c[k], i]; If[k == u, While[c[u] > 0, u++]]; Sow[u]; j = k; s += k, {i, 2, 2^12}]][[-1, -1]] (* _Michael De Vlieger, Jan 23 2022 *)
from itertools import islice from sympy import divisors def A253415_gen(): # generator of terms, first term is a(2) bset, m, s = {1}, 2, 3 while True: for d in divisors(s): if d not in bset: bset.add(d) while m in bset: m += 1 yield m s += d break A253415_list = list(islice(A253415_gen(),30)) # Chai Wah Wu, Jan 25 2022
import Data.List (insert)
a253443 n = a253443_list !! (n-4)
a253443_list = f (4, []) 6 where
f (m,ys) z = g $ dropWhile (< m) $ a027750_row' z where
g (d:ds) | elem d ys = g ds
| otherwise = m : f (ins [m, m+1 ..] (insert d ys)) (z + d)
ins (u:us) vs'@(v:vs) = if u < v then (u, vs') else ins us vs
-- Reinhard Zumkeller, Jan 03 2015
import Data.List (elemIndex); import Data.Maybe (fromJust) a109736 = (+ 1) . fromJust . (`elemIndex` a109890_list) -- Reinhard Zumkeller, Jan 01 2015
a[1] = 1; a[2] = 2; a[n_] := a[n] = Block[{t = Table[a[i], {i, n - 1}]}, s = Plus @@ t; d = Divisors[s]; l = Complement[d, t]; If[l != {}, k = First[l], k = s; While[Position[t, k] == {}, k += s]; k]]; t = Table[a[n], {n, 250}]; Table[k = 1; While[ t[[k]] != n, k++ ]; k, {n, 70}] (* Robert G. Wilson v, Aug 12 2005 *)
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