A200088 a(n) is the least number greater than a(n-1) such that the sum of the decimal digits of a(n-1) and a(n) is prime.

1, 2, 3, 4, 7, 13, 16, 19, 21, 22, 25, 28, 30, 31, 34, 37, 43, 46, 49, 51, 52, 55, 58, 60, 61, 64, 67, 73, 76, 79, 85, 88, 94, 97, 100, 101, 102, 103, 106, 109, 111, 112, 115, 118, 120, 121, 124, 127, 133, 136, 139, 141, 142, 145, 148, 150, 151, 154, 157

Offset

1,2

Comments

Resulting primes: 3, 5, 7, 11, 11, 11, 17, 13, 7, 11, 17, 13, 7, 11, 17, 17, 17, 23, 19, 13, 17, 23, 19, 13, 17, 23, 23, 23, 29, 29, 29, 29, 29.

Links

Table of n, a(n) for n=1..59.

Example

a(1)=1, a(2)=2, 1+2=3 prime,
a(5)=7, a(6)=13, 7+1+3=11 prime,
a(6)=13, a(7)=16, 1+3+1+6=11 prime.

Mathematica

t = {1}; Do[nxt = t[[-1]] + 1; While[! PrimeQ[Total[IntegerDigits[t[[-1]]]] + Total[IntegerDigits[nxt]]], nxt++]; AppendTo[t, nxt], {100}]; t (* T. D. Noe, Nov 14 2011 *)
nxt[b_]:=Module[{c=b+1}, While[!PrimeQ[Total[IntegerDigits[b]]+Total[IntegerDigits[c]]], c++]; c]; NestList[nxt, 1, 60] (* Harvey P. Dale, Sep 11 2023 *)

Crossrefs

Sequence in context: A023162 A022437 A057983 * A004783 A031149 A096723

Adjacent sequences: A200085 A200086 A200087 * A200089 A200090 A200091

Keyword

nonn,base

Author

Zak Seidov, Nov 13 2011

Extensions

Typo in example corrected by Vincenzo Librandi, Nov 13 2011

Status

approved