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.

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A244547 Numbers k with nonzero digits such that k +/- the product of digits of k are both palindromes.

Original entry on oeis.org

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

Views

Author

Derek Orr, Jun 29 2014

Keywords

Examples

			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.
		

Crossrefs

Programs

  • Mathematica
    Select[Range@100000,(p=#+{1,-1}*Times@@IntegerDigits@#; Differences@p!={0}&&AllTrue[p,PalindromeQ])&] (* Hans Rudolf Widmer, Sep 03 2023 *)
  • 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,", "))))

A244542 Palindromes n such that n +/- the product of digits of n are both palindromes.

Original entry on oeis.org

1, 2, 3, 4, 101, 202, 252, 303, 404, 505, 606, 707, 808, 909, 1001, 2002, 3003, 4004, 5005, 6006, 7007, 8008, 9009, 10001, 10101, 10201, 10301, 10401, 10501, 10601, 10701, 10801, 10901, 11011, 12021, 13031, 14041, 15051, 15451, 16061, 17071, 18081, 19091, 20002, 20102, 20202
Offset: 1

Views

Author

Derek Orr, Jun 29 2014

Keywords

Comments

These are the palindromes in A244541.
All palindromes with a zero will be in this sequence.
The palindromes that do not contain a zero but do satisfy the definition begin 1, 2, 3, 4, 252, 15451, 25152, 25252, 25352, 25452, 36563, 51415, 52125, 52225, 52325, 52425, 63536, 92529, 1455541, 1545451, 1954591 . . . - Harvey P. Dale, May 14 2019

Examples

			101 - 1*0*1 and 101 + 1*0*1 are both palindromes (still 101). So 101 is a member of this sequence.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[30000],AllTrue[#+{0,Times@@IntegerDigits[#],-Times@@IntegerDigits[#]},PalindromeQ]&] (* Harvey P. Dale, Aug 14 2025 *)
  • PARI
    rev(n)={r="";for(i=1,#digits(n),r=concat(Str(digits(n)[i]),r));return(eval(r))}
    for(n=1,10^5,if(rev(n)==n,dig=digits(n);p=prod(k=1,#dig,dig[k]);mi=n-p;ma=n+p;if(rev(mi)==mi&&rev(ma)==ma,print1(n,", "))))
Showing 1-2 of 2 results.