A081939 -id:A081939 - cp's OEIS frontend

A316497 a(n) = gcd(A081939(n), A081939(n+1)).

2, 2, 2, 2, 11, 11, 11, 11, 11, 11, 11, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 13, 5, 7, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 22, 22, 22, 22, 22, 22, 22, 22, 22, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 22, 22, 22, 22, 22, 22, 22, 22, 22, 11, 55

Offset: 1

Robert Israel, Jul 04 2018

			A081939(3)=6 and A081939(4)=8, so a(3)=gcd(6,8)=2.

Robert Israel, Table of n, a(n) for n = 1..10000
Index entries for sequences related to palindromes

Cf. A081939.

# with list R containing terms of A081939
seq(igcd(R[i],R[i+1]),i=1..nops(R)-1)

A083136 a(n+1) is the smallest palindrome greater than a(n) and relatively prime to a(n).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 202, 313, 323, 333, 343, 353, 363, 373, 383, 393, 404, 515, 606, 727, 737, 747, 757, 767, 777, 787, 797, 808, 919, 929, 939, 949, 959, 969, 979, 989, 999, 1001, 10001, 10101, 10201

Offset: 1

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Apr 24 2003

Subsequence of A002113. - Michel Marcus, May 25 2014

Contains at most one 2k-digit number for every k, since all such palindromes are divisible by 11. - Ivan Neretin, Aug 12 2015

Giovanni Resta, Table of n, a(n) for n = 1..10000

Cf. A002113, A081939.

spal[n_]:=Module[{k=n+1},While[!PalindromeQ[k]||!CoprimeQ[k,n],k++];k]; NestList[spal,1,60] (* Harvey P. Dale, May 09 2021 *)

ispal(n) = my(d=digits(n)); d == Vecrev(d);
lista(nn) = {print1(last = 1, ", "); for (n=2, nn, if (ispal(n) && gcd(n, last)== 1, print1(n, ", "); last = n;););} \\ Michel Marcus, Aug 12 2015

More terms from David Wasserman, Oct 19 2004

A081938 a(1) = 1, a(n) = smallest palindromic number > a(n-1) of the form k*a(n-1) - 1.

Original entry on oeis.org

1, 2, 3, 5, 9, 44, 131, 602206, 39293339293, 98576836066063867589

Offset: 1

Amarnath Murthy, Apr 02 2003

Cf. A081939.

nxt[n_]:=Module[{k=2},While[!PalindromeQ[k*n-1],k++];k*n-1]; Join[{1}, NestList[ nxt,2,8]] (* Harvey P. Dale, Oct 05 2018 *)

a(8) and a(9) from R. J. Mathar, Jul 15 2007

a(10) from Donovan Johnson, Mar 26 2011

cp's OEIS Frontend

A316497 a(n) = gcd(A081939(n), A081939(n+1)).

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A083136 a(n+1) is the smallest palindrome greater than a(n) and relatively prime to a(n).

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A081938 a(1) = 1, a(n) = smallest palindromic number > a(n-1) of the form k*a(n-1) - 1.

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