cp's OEIS Frontend

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.

A105417 Numbers that are pandigital in Roman numerals, using each of the symbols I, V, X, L, C, D and M at least once.

Original entry on oeis.org

1444, 1446, 1447, 1448, 1464, 1466, 1467, 1468, 1474, 1476, 1477, 1478, 1484, 1486, 1487, 1488, 1644, 1646, 1647, 1648, 1664, 1666, 1667, 1668, 1674, 1676, 1677, 1678, 1684, 1686, 1687, 1688, 1744, 1746, 1747, 1748, 1764, 1766, 1767, 1768, 1774, 1776
Offset: 1

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Author

Robert Happelberg (roberthappelberg(AT)yahoo.com), Apr 06 2005

Keywords

Comments

Contains A105416. The largest member of this sequence is 3888, MMMDCCCLXXXVIII.
From Daniel Forgues, Jul 31 2011: (Start)
There are 192 = 3 * 4^3 pandigital Roman numerals:
3 ways to start: M*, MM*, MMM* (since no Roman numeral stood for 5000)
4 ways for the hundreds: *CD*, *DC*, *DCC*, *DCCC*
4 ways for the decades: *XL*, *LX*, *LXX*, *LXXX*
4 ways for the units: *IV, *VI, *VII, *VIII (End)
Equivalently, numbers of the form abcd with 1 <= a <= 3 and b,c,d in {4,6,7,8}. - M. F. Hasler, Jul 10 2018

Examples

			a(3) = 1447 because its Roman numeral representation, MCDXLVII, uses each of the symbols V, X, L, C, D and M once and the symbol I twice.
		

Crossrefs

Programs

  • Haskell
    import Data.List (nub, sort)
    a105417 n = a105417_list !! (n-1)
    a105417_list = filter ((== "1234567") . sort . nub . show . a061493) [1..3999]
    -- Reinhard Zumkeller, Apr 14 2013
    
  • Maple
    with(StringTools): for n from 1 to 3999 do r:=convert(n,roman): if Search("I",r) > 0 and Search("V",r) > 0 and Search("X",r) > 0 and Search("L",r) > 0 and Search("C",r) > 0 and Search("D",r) > 0 and Search("M",r) > 0 then printf("%d, ", n): fi: od: # Nathaniel Johnston, May 18 2011
    A105417 := select(n->nops(convert(convert(n,roman),set))=7, `$`(3888)) # M. F. Hasler, Jul 10 2018
  • Mathematica
    Select[Range[900,1776],ContainsAll[Characters[RomanNumeral[#]],{"M","C","D","X","L","I","V"}]&] (* James C. McMahon, Jan 24 2024 *)
  • PARI
    A105417=vector(192,i,fromdigits(apply(d->d-!d,digits(i+63,4)))+555) \\ M. F. Hasler, Jul 10 2018

Formula

A006968(a(n)) >= 7. - Reinhard Zumkeller, Apr 14 2013