|
|
A050812
|
|
Number of times n is palindromic in bases b, 2 <= b <= 10.
|
|
9
|
|
|
9, 9, 8, 8, 7, 7, 5, 5, 4, 3, 3, 1, 1, 1, 1, 2, 2, 2, 2, 0, 2, 3, 1, 1, 2, 1, 2, 2, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 0, 3, 1, 1, 1, 1, 2, 2, 0, 1, 1, 2, 2, 2, 0, 1, 3, 1, 2, 0, 1, 1, 1, 1, 3, 1, 3, 1, 2, 1, 0, 1, 1, 1, 2, 1, 0, 0, 1, 2, 0, 3, 1, 2, 1, 0, 3
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,1
|
|
LINKS
|
|
|
EXAMPLE
|
a(121) = 4 since 121_10, 171_8, 232_7 and 11111_3 are palindromes.
|
|
MATHEMATICA
|
Table[Count[Table[IntegerDigits[n, b], {b, 2, 10}], _?(#==Reverse[#]&)], {n, 0, 90}] (* Harvey P. Dale, Aug 18 2012 *)
|
|
PROG
|
(Python)
from sympy.ntheory.digits import digits
def ispal(n, b):
digs = digits(n, b)[1:]
return digs == digs[::-1]
def a(n): return sum(ispal(n, b) for b in range(2, 11))
(PARI) a(n) = sum(b=2, 10, my(d=digits(n, b)); d == Vecrev(d)); \\ Michel Marcus, Sep 09 2021
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|