A160751 -id:A160751 - cp's OEIS frontend

A160954 a(n+1) is the smallest prime formed by appending a single digit to a(n); a(1)=18.

18, 181, 1811, 18119, 181193, 1811939

Offset: 1

Juri-Stepan Gerasimov, May 31 2009

There is no prime a(7) since 18119390 to 18119399 are all composite.

			a(1)=18,
a(2)=181,
a(3)=1811,
a(4)=18119,
a(5)=181193,
a(6)=1811939. [Corrected by _Jon E. Schoenfield_, Feb 18 2019]

Cf. A000040, A160751, A160955.

A160954 :=proc(n) option remember ; local d; if n =1 then 18; else for d from 1 to 9 by 2 do if isprime(10*prochame n+d) then RETURN(10*procnam n+d 0 ; fi; end:
seq(A160954(n), n=1..10) ; R. J. Mathar, May 26 2009

spsd[n_]:=SelectFirst[Table[10n+d,{d,{1,3,7,9}}],PrimeQ]; NestList[spsd,18,5] (* Harvey P. Dale, Aug 02 2024 *)

Redundant part of the definition removed by R. J. Mathar, May 21 2010

A160955 a(n+1) is the largest prime formed by appending a single digit to a(n); a(1)=18.

Original entry on oeis.org

18, 181, 1811, 18119, 181199, 1811993

Offset: 1

Juri-Stepan Gerasimov, May 31 2009

There is no prime a(7) since 18119930 to 18119939 are all composite.

			a(1)=18,
a(2)=181,
a(3)=1811,
a(4)=18119,
a(5)=181199,
a(6)=1811993. [Corrected by _Jon E. Schoenfield_, Feb 18 2019]

Cf. A000040, A160751, A160954.

A160955 :=proc(n) option remember ; local d; if n =1 then 18; else for d from 1 to 9 by 2 do if isprime(10*prochame n+d) then RETURN(10*procnam n+d 0 ; fi; end:
seq(A160955(n), n=1..10) ; # R. J. Mathar, May 26 2009

Redundant part of the definition removed by R. J. Mathar, May 21 2010

cp's OEIS Frontend

A160954 a(n+1) is the smallest prime formed by appending a single digit to a(n); a(1)=18.

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