A277111 Lesser of twin primes P(k) and P(k+1) such that Sd(P(k)) + Sd(P(k+1)) = Sd(k) + Sd(k+1), where Sd(x) is the sum of digits of x.

1619, 2309, 2339, 12239, 28109, 35081, 37307, 37571, 50549, 51059, 51719, 62129, 64919, 65729, 87539, 89519, 91079, 113759, 121439, 121631, 160649, 170351, 174329, 182129, 191249, 205949, 215459, 223679, 231839, 254039, 270269, 285119, 301841, 317489, 319829

Offset

1,1

Links

Table of n, a(n) for n=1..35.

Paolo P. Lava, First 60 couples [k, P(k)]

Example

P(256) = 1619, P(257) = 1621; Sd(256) + Sd(257) = 13 + 14 = 27 and Sd(1619) + Sd(1621) = 17 + 10 = 27.

Maple

T:=proc(w) local x, y, z; x:=w; y:=0; for z from 1 to ilog10(x)+1 do y:=y+(x mod 10); x:=trunc(x/10); od; y; end:
P:= proc(q) local a, b, k, n;
for n from 1 to q do if ithprime(n+1)-ithprime(n)=2 then if T(ithprime(n))+T(ithprime(n+1))=T(n)+T(n+1) then print(ithprime(n)); fi; fi; od; end: P(10^5);

Crossrefs

Cf. A001359, A033548.

Sequence in context: A231048 A231423 A252011 * A345597 A345856 A206537

Adjacent sequences: A277108 A277109 A277110 * A277112 A277113 A277114

Keyword

nonn,base,easy

Author

Paolo P. Lava, Sep 30 2016

Status

approved