A080837 Jouka numbers: either the number is divisible by 7 or 11 or has a 7 in its decimal representation.

7, 11, 14, 17, 21, 22, 27, 28, 33, 35, 37, 42, 44, 47, 49, 55, 56, 57, 63, 66, 67, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 84, 87, 88, 91, 97, 98, 99, 105, 107, 110, 112, 117, 119, 121, 126, 127, 132, 133, 137, 140, 143, 147, 154, 157, 161, 165, 167, 168, 170

Offset

1,1

Comments

Jouka numbers are used in drinking games. Whenever a person wrongly identifies a jouka number he or she has to drink a beer.

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Formula

a(n) ~ n. - Charles R Greathouse IV, Sep 10 2015

Example

a(1) = 7, a(2) = 11, since 7 is the first jouka number (divisible by 7) and 11 is the second.

Maple

A080837 := proc(n) option remember: local k: if(n=1)then return 7: fi: for k from procname(n-1)+1 do if(k mod 7=0 or k mod 11=0 or member(7, convert(k, base, 10)))then return k: fi: od: end: seq(A080837(n), n=1..60); # Nathaniel Johnston, May 26 2011

Mathematica

Select[Range[200], Divisible[#, 7]||Divisible[#, 11]||DigitCount[ #, 10, 7]> 0&] (* Harvey P. Dale, Jan 14 2017 *)

Prog

(PARI) is(n)=gcd(n, 77)>1 || setsearch(Set(digits(n)), 7) \\ Charles R Greathouse IV, Sep 10 2015
(Python)
def ok(n): return n%7 == 0 or n%11 == 0 or '7' in str(n)
print(list(filter(ok, range(1, 171)))) # Michael S. Branicky, Jul 11 2021

Crossrefs

Sequence in context: A153049 A065105 A118797 * A168135 A225858 A120687

Adjacent sequences: A080834 A080835 A080836 * A080838 A080839 A080840

Keyword

nonn,easy,base

Author

Sander and Pieter (eendebak(AT)math.uu.nl), Mar 28 2003

Extensions

Terms after a(34) from Nathaniel Johnston, May 26 2011

Status

approved