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.
Filtered([1..10000],n->PowerMod(10,n,n)=0); # Muniru A Asiru, Mar 19 2019
import Data.Set (singleton, deleteFindMin, insert)
a003592 n = a003592_list !! (n-1)
a003592_list = f $ singleton 1 where
f s = y : f (insert (2 * y) $ insert (5 * y) s')
where (y, s') = deleteFindMin s
-- Reinhard Zumkeller, May 16 2015
[n: n in [1..10000] | PrimeDivisors(n) subset [2,5]]; // Bruno Berselli, Sep 24 2012
isA003592 := proc(n) if n = 1 then true; else return (numtheory[factorset](n) minus {2,5} = {} ); end if; end proc: A003592 := proc(n) option remember; if n = 1 then 1; else for a from procname(n-1)+1 do if isA003592(a) then return a; end if; end do: end if; end proc: # R. J. Mathar, Jul 16 2012
twoFiveableQ[n_] := PowerMod[10, n, n] == 0; Select[Range@ 10000, twoFiveableQ] (* Robert G. Wilson v, Jan 12 2012 *) twoFiveableQ[n_] := Union[ MemberQ[{1, 3, 7, 9}, # ] & /@ Union@ Mod[ Rest@ Divisors@ n, 10]] == {False}; twoFiveableQ[1] = True; Select[Range@ 10000, twoFiveableQ] (* Robert G. Wilson v, Oct 26 2010 *) maxExpo = 14; Sort@ Flatten@ Table[2^i * 5^j, {i, 0, maxExpo}, {j, 0, Log[5, 2^(maxExpo - i)]}] (* Or *) Union@ Flatten@ NestList[{2#, 4#, 5#} &, 1, 7] (* Robert G. Wilson v, Apr 16 2011 *)
list(lim)=my(v=List(),N);for(n=0,log(lim+.5)\log(5),N=5^n;while(N<=lim,listput(v,N);N<<=1));vecsort(Vec(v)) \\ Charles R Greathouse IV, Jun 28 2011
# A003592.py from heapq import heappush, heappop def A003592(): pq = [1] seen = set(pq) while True: value = heappop(pq) yield value seen.remove(value) for x in 2*value, 5*value: if x not in seen: heappush(pq, x) seen.add(x) sequence = A003592() A003592_list = [next(sequence) for _ in range(100)]
from sympy import integer_log def A003592(n): def bisection(f,kmin=0,kmax=1): while f(kmax) > kmax: kmax <<= 1 kmin = kmax >> 1 while kmax-kmin > 1: kmid = kmax+kmin>>1 if f(kmid) <= kmid: kmax = kmid else: kmin = kmid return kmax def f(x): return n+x-sum((x//5**i).bit_length() for i in range(integer_log(x,5)[0]+1)) return bisection(f,n,n) # Chai Wah Wu, Feb 24 2025
def isA003592(n) : return not any(d != 2 and d != 5 for d in prime_divisors(n)) @CachedFunction def A003592(n) : if n == 1 : return 1 k = A003592(n-1) + 1 while not isA003592(k) : k += 1 return k [A003592(n) for n in (1..48)] # Peter Luschny, Jul 20 2012
a(n)=if(n<1,n==0,a(n\2)+a(n\4))
a[0]=1;a[n_]:=a[n]=a[Floor[n/2]]+a[Floor[n/3]];Array[a,75,0] (* Harvey P. Dale, Aug 23 2020 *)
a(n)=if(n<1,n==0,a(n\2)+a(n\3))
a007731 n = a007731_list !! n a007731_list = 1 : (zipWith3 (\u v w -> u + v + w) (map (a007731 . (`div` 2)) [1..]) (map (a007731 . (`div` 3)) [1..]) (map (a007731 . (`div` 6)) [1..])) -- Reinhard Zumkeller, Jan 11 2014
A007731 := proc(n) option remember; if n=0 then RETURN(1) else RETURN( A007731(trunc(n/2))+A007731(trunc(n/3))+A007731(trunc(n/6))); fi; end; # second Maple program: a:= proc(n) option remember; `if`(n=0, 1, add(a(floor(n/i)), i=[2, 3, 6])) end: seq(a(n), n=0..100); # Alois P. Heinz, Sep 27 2023
a[n_] := a[n] = a[Floor[n/2]] + a[Floor[n/3]] + a[Floor[n/6]] ; a[0] = 1; Table[a[n], {n, 0, 60}] (* Jean-François Alcover, Mar 06 2014 *)
a(n)=if(n<5, 2*n+1, a(n\2) + a(n\3) + a(n\6)) \\ Charles R Greathouse IV, Feb 08 2017
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