A191992 Concatenation of n and the n-th composite number.

14, 26, 38, 49, 510, 612, 714, 815, 916, 1018, 1120, 1221, 1322, 1424, 1525, 1626, 1727, 1828, 1930, 2032, 2133, 2234, 2335, 2436, 2538, 2639, 2740, 2842, 2944, 3045, 3146, 3248, 3349, 3450, 3551, 3652, 3754, 3855, 3956, 4057, 4158, 4260, 4362, 4463, 4564, 4665, 4766, 4868, 4969, 5070, 5172, 5274, 5375, 5476

Offset: 1

Author

Kausthub Gudipati, Jun 20 2011

Keywords

• nonn
• base

Links

• Jens Kruse Andersen, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A045532, the prime analog of this sequence.

Cf. A246801, primes in this sequence.

Programs

Mathematica

Module[{upto=55,cmps,len},cmps=Select[Range[10*upto],CompositeQ];len= Min[ Length[ cmps],upto];#[[1]]*10^IntegerLength[#[[2]]]+#[[2]]&/@ Thread[{ Range[ len],Take[cmps,len]}]] (* Harvey P. Dale, Dec 05 2016 *)

PARI

n=0;for(k=4,1e3,if(isprime(k),k++);print1(n++k", ")) \\ Charles R Greathouse IV, Jun 21 2011