login
A244547
Numbers k with nonzero digits such that k +/- the product of digits of k are both palindromes.
1
1, 2, 3, 4, 247, 252, 348, 843, 15451, 25152, 25252, 25352, 25452, 36563, 36968, 44594, 51165, 51415, 52125, 52225, 52325, 52425, 63536, 92529, 1455541, 1545451, 1595451, 1954591, 2255522, 2524752, 2525252, 2534852, 2584352, 2853582, 2856582, 3159563, 3354533, 3524753, 3534353
OFFSET
1,2
EXAMPLE
247 has all digits > 0. 247 - 2*4*7 = 191 is a palindrome, and 247 + 2*4*7 = 303 is a palindrome. Thus 247 is a member of this sequence.
MATHEMATICA
Select[Range@100000, (p=#+{1, -1}*Times@@IntegerDigits@#; Differences@p!={0}&&AllTrue[p, PalindromeQ])&] (* Hans Rudolf Widmer, Sep 03 2023 *)
PROG
(PARI) rev(n)={r=""; for(i=1, #digits(n), r=concat(Str(digits(n)[i]), r)); return(eval(r))}
for(n=1, 10^7, dig=digits(n); p=prod(k=1, #dig, dig[k]); if(p!=0, mi=n-p; ma=n+p; if(rev(mi)==mi&&rev(ma)==ma, print1(n, ", "))))
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Derek Orr, Jun 29 2014
STATUS
approved