This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A262958 Numbers whose base-b expansions, for both b=3 and b=4, include no digits other than 1 and b-1. 4
 1, 5, 7, 13, 23, 53, 125, 215, 373, 1367, 1373, 1375, 3551, 4093, 5471, 5495, 5503, 30581, 30589, 32765, 32767, 56821, 56831, 89557, 96119, 96215, 96223, 97655, 98135, 98141, 98143, 98167, 98293, 98303, 351743, 352093, 521599, 521693, 521717, 521719, 524119, 524149, 875893, 875903, 884725, 884735 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS 1, 7 and 32767 also share this property in base 2; their binary expansions consist only of a sequence of 1s. LINKS Chai Wah Wu, Table of n, a(n) for n = 1..10000 EXAMPLE 53 is 1222 in base 3 and 311 in base 4; it only uses the digit 1 or the largest digit in the two bases and is therefore a term. Similarly 215 is 21222 in base 3 and 3113 in base 4 so it is also a term. MATHEMATICA Select[Range@ 1000000, Last@ DigitCount[#, 3] == 0 && Total@ Rest@ Drop[DigitCount[#, 4], {3}] == 0 &] (* Michael De Vlieger, Oct 05 2015 *) Join[{1, 5}, Flatten[Table[Select[FromDigits[#, 3]&/@Tuples[{1, 2}, n], Union[ IntegerDigits[ #, 4]] =={1, 3}&], {n, 20}]]] (* Harvey P. Dale, Jun 14 2016 *) PROG (PARI) is(n)=!setsearch(Set(digits(n, 3)), 0) && #setintersect(Set(digits(n, 4)), [0, 2])==0 \\ Charles R Greathouse IV, Oct 12 2015 (Python) from gmpy2 import digits def f1(n):     s = digits(n, 3)     m = len(s)     for i in range(m):         if s[i] == '0':             return(int(s[:i]+'1'*(m-i), 3))     return n def f2(n):     s = digits(n, 4)     m = len(s)     for i in range(m):         if s[i] == '0':             return(int(s[:i]+'1'*(m-i), 4))         if s[i] == '2':             return(int(s[:i]+'3'+'1'*(m-i-1), 4))     return n A262958_list = [] n = 1 for i in range(10**4):     m = f2(f1(n))     while m != n:         n, m = m, f2(f1(m))     A262958_list.append(m)     n += 1 # Chai Wah Wu, Oct 30 2015 CROSSREFS Cf. A207079, A258981, A261970. Sequence in context: A201474 A078724 A191022 * A155757 A027674 A124307 Adjacent sequences:  A262955 A262956 A262957 * A262959 A262960 A262961 KEYWORD nonn,base AUTHOR Robin Powell, Oct 05 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 18 18:20 EDT 2019. Contains 327178 sequences. (Running on oeis4.)