A053780 -id:A053780 - cp's OEIS frontend

A171706 The first n-fold intrinsically 7-palindromic number (represented in base 10).

65, 186621, 3360633

Offset: 1

James G. Merickel, Dec 16 2009

Though this sequence is apt to never have many known members, its third is quite a nice coincidence for consideration.
A029965 runs just short of space to show it, and A053780 is a totally unrelated collection of palindromes that also includes 33633 in addition to 3360633.
a(4) > 10^17. - Hiroaki Yamanouchi, Aug 22 2015

			a(2)=186621 is 3555553 in base 6 and 1405041 in base 7.
a(3)=3360633 is 6281826 in base 9 and 1995991 in base 11.

Cf. A171701, A171702, A171703, A171704, A171705, A171741, A029966, A029965, A053780.

Typo in third term corrected by James G. Merickel, Dec 18 2009

A171741 The first 3-fold intrinsically n-palindromic number (given in base ten).

Original entry on oeis.org

18, 154, 19040, 267140, 2853326516320, 3360633

Offset: 2

James G. Merickel, Dec 17 2009

The large value for the 6-palindrome case, a(6)=2853326516320, has 139 as the smallest of the three bases.
Coincidentally, the following much shorter term, a(7)= 3360633, involves base 9 through 11, the conjunction of base-9 and base-10 palindromes (A029965) comes up a term short (assuming space limitations remain as they are at the beginning of 2011), and A053740 is a totally unrelated collection of palindromes that also contains 33633.
a(8) > 10^18. - Hiroaki Yamanouchi, Aug 22 2015

			a(5)=267140 is 6D4D6 in base 14, 54245 in base 15, and 29E92 in base 18.
a(7)=3360633 is 6281826 in base 9 and 1995991 in base 11.

Cf. A171701, A171702, A171703, A171704, A171705, A171706, A171740, A171742, A053780, A029966, A029965.

A053779 Numbers k such that the sum of the first k composite numbers is palindromic.

Original entry on oeis.org

1, 22, 24, 167, 202, 226, 1443, 2380, 3190, 3952, 4220, 16827, 26304, 37612, 40813, 213501, 376524, 1920079, 2061085, 2635057, 3463613, 4268588, 16513206, 68101132, 166428703, 207224360, 403784450, 421279478, 1384813481

Offset: 1

G. L. Honaker, Jr., Mar 29 2000

Sequence lists numbers k such that 4 + 6 + 8 + 9 + 10 + 12 + ... + composite(k) is palindromic. For the corresponding values of composite(k) see A057959.

P. De Geest, Palindromic Sums
C. Rivera, PrimePuzzle 89

Cf. A002808, A002113, A053780.

Position[Accumulate[Select[Range[146*10^7],CompositeQ]],?(PalindromeQ[ #] &)] // Flatten (* _Harvey P. Dale, Sep 29 2018 *)

More terms from G. L. Honaker, Jr., Mar 29 2000

Further terms added by Patrick De Geest, Nov 15 2000

A057959 Sum of composite numbers up to n is palindromic.

Original entry on oeis.org

4, 34, 36, 215, 258, 288, 1711, 2785, 3708, 4572, 4873, 18986, 29509, 42005, 45534, 234272, 411232, 2074123, 2225480, 2841251, 3728941, 4590401, 17643216, 72349270, 176262062, 219311147, 426454179, 444875288, 1457527586

Offset: 1

G. L. Honaker, Jr. and Patrick De Geest, Nov 15 2000

Sequence is 4 + 6 + 8 + 9 + 10 + 12 + ... + n.

Patrick De Geest, Palindromic Sums.
Carlos Rivera, Puzzle 89, The Prime Puzzles & Problems Connection.

Cf. A002113, A002808, A053779, A053780.

a(n) = A002808(A053779(n)). - R. J. Mathar, Sep 09 2015

cp's OEIS Frontend

A171706 The first n-fold intrinsically 7-palindromic number (represented in base 10).

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A171741 The first 3-fold intrinsically n-palindromic number (given in base ten).

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A053779 Numbers k such that the sum of the first k composite numbers is palindromic.

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A057959 Sum of composite numbers up to n is palindromic.

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