A074843 Quadruplets: base 10 representation is the juxtaposition of four identical strings.

1111, 2222, 3333, 4444, 5555, 6666, 7777, 8888, 9999, 10101010, 11111111, 12121212, 13131313, 14141414, 15151515, 16161616, 17171717, 18181818, 19191919, 20202020, 21212121, 22222222, 23232323, 24242424, 25252525

Offset: 1

Author

Felice Russo, Sep 10 2002

Keywords

• easy
• nonn
• base

Comments

Doublets in which the index is also a doublet. - Jamie Robert Creasey, Jun 23 2021

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A020338.

Programs

Mathematica

Table[FromDigits[Flatten[IntegerDigits/@PadRight[{},4,n]]],{n,30}] (* Harvey P. Dale, Dec 20 2021 *)

PARI

a(n)=eval(Str(n,n,n,n)) \\ Charles R Greathouse IV, Jun 23 2021

UBASIC

10 cls 30 for I=1 to 100 40 A=str(I) 50 C=A+A+A+A 60 B=val(cutspc(C)) 80 print B 90 next 100 end

Formula

A020338(A020338(n)). - Jamie Robert Creasey, Jun 23 2021