A113942 - OEIS

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A113942

Concatenating n with n+1 (in base 10) gives a number which is the product of 2 palindromes.

1, 4, 5, 115, 148, 247, 346, 371, 445, 528, 7606, 8376, 9157, 12478, 16528, 19834, 22477, 25103, 28546, 31989, 32476, 33057, 38875, 40495, 42475, 45761, 46335, 50494, 52474, 52647, 59533, 61483, 62473, 66445, 72472, 83461, 94450, 1165288

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

OFFSET

1,2

COMMENTS

Members that have an even number of digits are rare: 7606, 8376, 9157, ..., . - Robert G. Wilson v

LINKS

Table of n, a(n) for n=1..38.

EXAMPLE

3305733058 = 45454*72727.

MATHEMATICA

palQ[n_] := Block[{id = IntegerDigits[n]}, id == Reverse[id]]; t = {}; Do[p = 10^Floor[Log[10, n] + 1]n + n + 1; If[ MemberQ[ Union[Times @@@ Tuples[ Select[ Most@ Rest@ Divisors@p, palQ[ # ] &], 2]], p], AppendTo[t, n]], {n, 1504947}]; t (* Robert G. Wilson v, Jan 31 2006 *)

CROSSREFS

Sequence in context: A331584 A052320 A079197 * A073129 A270551 A041409

Adjacent sequences: A113939 A113940 A113941 * A113943 A113944 A113945

KEYWORD

base,nonn

AUTHOR

Giovanni Resta, Jan 31 2006

STATUS

approved