|
|
A248422
|
|
Even integers concatenated with themselves.
|
|
3
|
|
|
22, 44, 66, 88, 1010, 1212, 1414, 1616, 1818, 2020, 2222, 2424, 2626, 2828, 3030, 3232, 3434, 3636, 3838, 4040, 4242, 4444, 4646, 4848, 5050, 5252, 5454, 5656, 5858, 6060, 6262, 6464, 6666, 6868, 7070, 7272, 7474, 7676, 7878, 8080, 8282, 8484, 8686, 8888, 9090, 9292, 9494, 9696, 9898, 100100
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
a(n) = 2*n*10^ceiling(log_10(2*n)) + 2*n. - Tom Edgar, Oct 21 2014
|
|
MATHEMATICA
|
FromDigits[Flatten[IntegerDigits/@#]]&/@Partition[With[{c=2*Range[ 50]}, Riffle[c, c]], 2] (* or *) Table[n*10^IntegerLength[n]+n, {n, 2, 100, 2}] (* Harvey P. Dale, Jun 11 2019 *)
|
|
PROG
|
(PARI) a(n) = eval(concat(Str(2*n), Str(2*n))); \\ Michel Marcus, Oct 06 2014
(Magma) [Seqint(Intseq(n) cat Intseq(n)): n in [2..100 by 2]]; // Vincenzo Librandi, Oct 21 2014
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|