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
-
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 *)
A058849
Sum of odd composites up to n is palindromic.
Original entry on oeis.org
9, 55, 99, 215, 357, 663, 3725, 6321, 26999, 191363, 675861, 4073533, 4180943, 5540147, 6531789, 400974175, 4248550291, 6224149881, 17109266357, 38023877981, 55995454633, 62836534343, 212955815417
Offset: 1
-
nextA071904 := proc(n) local a ; a := n + 2 - ((n+1) mod 2); while isprime(a) do a := a+2 ; od ; RETURN(a) ; end: isA002113 := proc(n) local drev,i ; drev := convert(n,base,10) ; for i from 1 to nops(drev)/2 do if op(i,drev) <> op(-i,drev) then RETURN(false) ; fi ; od ; RETURN(true) ; end: nextA058844 := proc(n,nsum) local a, asum ; a := nextA071904(n) ; asum := nsum+a ; while not isA002113(asum) do a := nextA071904(a) ; asum := asum+a ; od ; RETURN([a, asum]) ; end: n := 9 ; nsum := 9 ; nnsum := [n,nsum] ; for i from 1 to 40 do print(op(1,nnsum)) ; nnsum := nextA058844(op(1,nnsum),op(2,nnsum)) ; od : # R. J. Mathar, Jan 29 2007
A118129
Numbers k such that the sum of the first k odd composites is palindromic in base 3.
Original entry on oeis.org
6, 14, 20, 424, 1042, 8290, 20802, 21644, 440512, 548008, 749171, 4366390, 5378548, 9850174, 17930596, 36158854, 130427194, 407305710, 3077094752, 93416875260
Offset: 1
The sum of the first 14 odd composites, when written in base 3, is the palindrome 201102, so 14 is in the sequence.
Cf.
A058848 (palindromic in base 10).
A118128
Numbers n such that the sum of the first n odd composites is palindromic in base 2.
Original entry on oeis.org
1, 3, 7, 19, 137, 139, 155, 379, 1509, 4877, 9509, 13015, 44819, 75595, 245027, 804463, 1082053, 1154293, 5802669, 10186839, 52333761, 81509017, 130656729, 375417331, 476594459, 1955429145, 9051994251, 12788782787
Offset: 1
The sum of the first 19 odd composites, when written in binary, is the palindrome 1101111011, so 19 is in the sequence.
Cf.
A058848 (palindromic in base 10).
Showing 1-4 of 4 results.
Comments