A156606 a(n)=number of even digits in prime(n) + number of prime digits in prime(n).

2, 1, 1, 1, 0, 1, 1, 0, 3, 2, 1, 2, 1, 2, 2, 2, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 2, 1, 1, 3, 1, 2, 1, 1, 1, 2, 2, 2, 2, 1, 1, 0, 1, 1, 0, 2, 5, 5, 4, 4, 3, 3, 3, 4, 4, 3, 3, 4, 3, 4, 3, 3, 1, 2, 2, 2, 3, 3, 2, 3, 2, 3, 3, 2, 3, 2, 2, 2, 2, 1, 3, 2, 3, 2, 3

Offset

1,1

Comments

Even digits are 2, 4, 6 or 8 and prime digits are 2, 3, 5 or 7.

Links

Table of n, a(n) for n=1..86.

Example

If prime(1)=2(even, prime), then 1+1=2=a(1). If prime(2)=3(0, prime), then 0+1=1=a(2). If prime(3)=5(0, prime), then 0+1+1=a(3). If prime(4)=7(0, prime), then 0+1=1+a(4). If prime(5)=11(0, 0), then 0+0=0=a(5), etc.

Maple

npris := proc(n) local dgs, a, i ; dgs := convert(n, base, 10) ; a := 0 ; for i in dgs do if isprime(i) then a := a+1 ; fi; od: a ; end: nevsnot0 := proc(n) local dgs, a, i ; dgs := convert(n, base, 10) ; a := 0 ; for i in dgs do if i mod 2 = 0 and i <> 0 then a := a+1 ; fi; od: a ; end: for n from 1 to 800 do p := ithprime(n) ; printf("%d, ", nevsnot0(p)+npris(p)) ; od: # R. J. Mathar, Feb 13 2009

Mathematica

nepd[n_]:=Module[{p=IntegerDigits[Prime[n]]}, Count[p, _?EvenQ]+Count[ p, _?PrimeQ]]; Array[nepd, 120] (* Harvey P. Dale, Dec 09 2017 *)

Crossrefs

Sequence in context: A053252 A261029 A117195 * A324606 A194087 A107034

Adjacent sequences: A156603 A156604 A156605 * A156607 A156608 A156609

Keyword

nonn,base,less

Author

Juri-Stepan Gerasimov, Feb 11 2009

Extensions

Corrected by Harvey P. Dale, Dec 09 2017

Status

approved