A028336 - OEIS

A028336

Positive numbers k such that k*(k+1) is a palindrome.

1, 2, 16, 77, 538, 1621, 2457, 5291, 5313, 52008, 142401, 143498, 1610151, 1713543, 4670028, 5218983, 15137566, 15282411, 15814148, 47370058, 50702751, 142594226, 166691108, 1694576061, 2554554552, 25541432472, 47878213558, 77714915542, 155482156418

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

For additional terms, see the De Geest link.

REFERENCES

Elena Deza and Michel Marie Deza, Figurate numbers, World Scientific Publishing (2012), page 278.

LINKS

Table of n, a(n) for n=1..29.

Patrick De Geest, Palindromic pronic numbers of the form n(n+1).

Eric Weisstein's World of Mathematics, Palindromic Number.

Eric Weisstein's World of Mathematics, Pronic Number.

MATHEMATICA

Select[Range[500000], PalindromeQ[#(#+1)] &] (* or *) Select[Range[50000], IntegerDigits[#(#+1)] == Reverse[ IntegerDigits[#(#+1)]] &] (* G. C. Greubel, Nov 24 2016 *)

PROG

(PARI) isok(k) = my(d = digits(k*(k+1))); Vecrev(d) == d; \\ Michel Marcus, Nov 09 2017

CROSSREFS

Cf. A008509, A028337.

Sequence in context: A323297 A034581 A356372 * A244717 A208102 A382947

Adjacent sequences: A028333 A028334 A028335 * A028337 A028338 A028339

KEYWORD

nonn,base

AUTHOR

Patrick De Geest

EXTENSIONS

More terms from Jon E. Schoenfield, Nov 09 2017

STATUS

approved