A058849 -id:A058849 - cp's OEIS frontend

A058848 Numbers k such that the sum of the first k odd composites is palindromic.

1, 12, 25, 61, 108, 211, 1344, 2339, 10539, 78409, 283181, 1748747, 1795423, 2386702, 2819089, 179101605, 1923088106, 2822581688, 7794689270, 17381011919, 25635268093, 28780043265, 97973526253

Offset: 1

Patrick De Geest, Dec 15 2000

Sequence of odd composite numbers is 9 + 15 + 21 + 25 + 27 + 33 + ... + z. For values of z see A058849.

Patrick De Geest, Palindromic Sums

Cf. A058849, A058850, A262044.

Position[Accumulate[Select[Range[9,10^7,2],CompositeQ]],?(PalindromeQ[#]&)]//Flatten (* The program generates the first 15 terms of the sequence. *) (* _Harvey P. Dale, Aug 05 2025 *)

a(20) from Donovan Johnson, Sep 01 2012
a(21)-a(23) from Chai Wah Wu, Dec 06 2019
Comment clarified by Harvey P. Dale, Aug 05 2025

A058850 Palindromes that are the sum of consecutive initial odd composites.

Original entry on oeis.org

9, 404, 1441, 7227, 20802, 73337, 2576752, 7576757, 144666441, 7584554857, 96520502569, 3584243424853, 3776886886773, 6651010101566, 9260919190629, 36028948184982063, 4095836722276385904, 8806146443446416088, 66832347055074323866, 331143864040468341133, 719190811555118091917, 906041488626884140609, 10450905369496350905401

Offset: 1

Patrick De Geest, Dec 15 2000

9 + 15 + 21 + 25 + 27 + 33 + ... + z = n. For values of z see A058849.

P. De Geest, Palindromic Sums

Cf. A058848, A058849.

Module[{nn=35000001,c},c=Complement[Range[9,nn,2],Prime[Range[ PrimePi[ nn]]]]; Select[ Accumulate[c],IntegerDigits[#] == Reverse[ IntegerDigits[ #]]&]] (* This program generates the first 15 terms of the sequence.  To generate more, increase the value of nn. *) (* Harvey P. Dale, Sep 02 2012 *)

a(19)-a(20) from Donovan Johnson, Sep 01 2012

a(21)-a(23) from Chai Wah Wu, Dec 06 2019

cp's OEIS Frontend

A058848 Numbers k such that the sum of the first k odd composites is palindromic.

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