A163602 First differences of A161753.

1, 15, 20, 28, 17, 19, 44, 52, 29, 31, 68, 76, 41, 43, 92, 49, 51, 53, 55, 116, 124, 65, 67, 69, 71, 148, 77, 79, 164, 172, 89, 91, 188, 97, 99, 101, 103, 212, 109, 111, 113, 115, 236, 244, 125, 127, 129, 131, 268, 137, 139, 284, 292, 149, 151, 153, 155, 316, 161, 163, 332

Offset: 1

Author

Juri-Stepan Gerasimov, Aug 01 2009

Keywords

• nonn
• easy

Examples

			a(1)=1=1^2-0^2. a(2)=15=4^2-1^2. a(3)=20=6^2-4^2.
		

Links

• G. C. Greubel, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A001248, A141468, A161753.

Programs

Maple

A141468 := proc(n) if n <= 2 then n-1 ; else for a from procname(n-1)+1 do if not isprime(a) then RETURN(a) ; fi; od: fi; end;
A161753 := proc(n) A141468(n)^2 ; end:
A163602 := proc(n) A161753(n+1)-A161753(n) ; end: seq(A163602(n),n=1..100) ; # R. J. Mathar, Aug 07 2009

Mathematica

A161753 := With[{nn = 500}, Complement[Range[0, nn], Prime[Range[PrimePi[nn]]]]^2]; Table[A161753[[n + 1]] - A161753[[n]], {n, 1, 50}] (* G. C. Greubel, Jul 29 2017 *)
Differences[With[{nn=100},Complement[Range[0,nn],Prime[Range[ PrimePi[ nn]]]]^2]] (* Harvey P. Dale, Mar 03 2020 *)

Formula

a(n) = A161753(n+1) - A161753(n).

Extensions

a(6) corrected by R. J. Mathar, Aug 07 2009