login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A003098 Palindromic triangular numbers.
(Formerly M2605)
14
0, 1, 3, 6, 55, 66, 171, 595, 666, 3003, 5995, 8778, 15051, 66066, 617716, 828828, 1269621, 1680861, 3544453, 5073705, 5676765, 6295926, 35133153, 61477416, 178727871, 1264114621, 1634004361, 5289009825, 6172882716, 13953435931 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Charles W. Trigg, Palindromic Triangular Numbers, J. Rec. Math., 6 (1973), 146-147.

David Wells, The Penguin Dictionary of Curious and Interesting Numbers, p. 73 (Rev. ed. 1997)

LINKS

T. D. Noe, Table of n, a(n) for n = 1..148 (from P. De Geest)

P. De Geest, Palindromic Triangulars

MATHEMATICA

palQ[n_]:=Module[{idn=IntegerDigits[n]}, idn==Reverse[idn]]; Select[Accumulate[Range[200000]], palQ]  (* Harvey P. Dale, Mar 23 2011 *)

CROSSREFS

Cf. A008509, A002113, A000217.

Sequence in context: A032070 A066569 A051641 * A045914 A067610 A067609

Adjacent sequences:  A003095 A003096 A003097 * A003099 A003100 A003101

KEYWORD

nonn,base,easy,nice

AUTHOR

N. J. A. Sloane

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 2 13:26 EST 2016. Contains 278678 sequences.