The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A073901 Number of primes with nonzero digits and digit sum n. 3
 0, 2, 1, 3, 7, 0, 29, 27, 0, 90, 234, 0, 753, 1025, 0, 3876, 9242, 0, 32549, 50112, 0, 180092, 420318, 0, 1525141, 2467286, 0, 9248093, 20668960, 0, 76318859 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(3k) = 0 for all k>1. The number of candidates to consider for a(n) (i.e. the number of integers with nonzero digits and digit sum n) is A104144(n+8). - Robert Israel, Jun 05 2015 LINKS Manfred Scheucher, Sage Script EXAMPLE a(2) = 2: the two primes are 2 and 11. a(5) = 7: the primes are 5, 41, 23, 113, 131, 311 and 2111. MAPLE S[1, 1]:= [1]: for x from 2 to 9 do S[1, x]:= [] od: a[1]:= 0: a[2]:= 2: for n from 2 to 22 do   for x from 2 to 9 do S[n, x]:= map(`+`, S[n-1, x-1], 1) od:   S[n, 1]:= [seq(op(map(t -> 10*t+1, S[n-1, x])), x=1..9)];   if n > 3 and n mod 3 = 0 then a[n]:= 0   else     if n > 5 then X:= [1, 3, 7, 9] else X:= [\$1..9] fi;     a[n]:= add(numboccur(map(isprime, S[n, x]), true), x=X);   fi od: seq(a[n], n=1..22); # Robert Israel, Jun 05 2015 MATHEMATICA f[n_] := If[ Mod[n, 3] == 0 && n > 3, 0, Block[{ip = IntegerPartitions@ n, lng = 1 + PartitionsP@ n, cnt = 0, k = 1}, While[k < lng, If[ Max@ ip[[k]] < 10, cnt += Length@ Select[ FromDigits@# & /@ Permutations@ ip[[k]], PrimeQ]]; k++]; cnt]]; Array[f, 30] (* Robert G. Wilson v, Jun 05 2015 *) DigitSum[n_, b_:10] := Total[IntegerDigits[n, b]]; nextodd[c_] := If[ Length[c]==2, Join[ Table[1, {c[[1]]-2}], {c[[2]]+2}], Join[ Table[1, {c[[1]]-1}], {c[[2]]+1}, Drop[c, 2]]]; a[2]=2; a[n_] := If[Mod[n, 3]==0 && n>3, 0, Module[{c, ct}, For[ c = Table[1, {n}]; ct = 0, True, c = nextodd[c], If[ PrimeQ[ FromDigits[c]] && DigitSum[FromDigits[c]]==n, ct++ ]; If[ c[[ -1]] >= n-1, Return[ct]] ] ]]; Table[ a[n], {n, 20}] CROSSREFS Not the same as A116381. Cf. A104144. Sequence in context: A140644 A321651 A326308 * A116381 A176120 A220621 Adjacent sequences:  A073898 A073899 A073900 * A073902 A073903 A073904 KEYWORD base,more,nonn AUTHOR Amarnath Murthy, Aug 18 2002 EXTENSIONS Edited and extended by Robert G. Wilson v, Sep 19 2002 a(20) to a(24) and alternate Mathematica coding from Dean Hickerson, Sep 21 2002 a(25) from Robert G. Wilson v, Sep 26 2002 a(26)-a(31) from Robert G. Wilson v, Nov 14 2005 Corrected and edited by Manfred Scheucher, Jun 01 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified November 27 16:20 EST 2021. Contains 349394 sequences. (Running on oeis4.)