A259041 Numbers n such that digital root of n is 4*(digital root of n-th prime).

26, 31, 58, 71, 89, 107, 112, 116, 157, 161, 193, 211, 247, 310, 337, 395, 458, 490, 503, 535, 580, 584, 620, 688, 769, 778, 841, 850, 859, 868, 872, 877, 895, 949, 985, 989, 1034, 1070, 1079, 1102, 1106, 1133, 1138, 1142, 1192, 1201, 1210, 1214, 1219, 1232, 1255, 1277, 1282, 1295, 1300, 1327, 1412, 1493, 1511, 1538

Offset: 1

Author

Zak Seidov, Jun 17 2015

Keywords

• nonn
• base

Comments

Corresponding primes:

101, 127, 271, 353, 461, 587, 613, 641, 919, 947, 1171, 1297, 1567, 2053, 2269, 2711, 3251, 3511, 3593, 3853, 4231, 4259, 4583, 5167, 5851, 5923, 6481, 6571, 6661, 6733, 6779, 6823, 6967, 7489, 7759, 7823, 8237, 8597, 8669, 8839, 8867, 9137, 9181, 9209, 9649, 9739, 9811, 9839, 9883.

Conjecture: a(n) ~ 27n. - Charles R Greathouse IV, Jun 18 2015

Crossrefs

Cf. A010888, A038194, A258876, A258877, A259032, A259040.

Programs

Mathematica

Reap[Do[If[FixedPoint[Total[IntegerDigits[#]]&,n]==4*Mod[Prime[n],9], Sow[{n,Prime[n]}]],{n,2000}]][[2,1]]

PARI

n=0; forprime(p=2, 1e4, if(p%9*4==n++%9, print1(n", "))) \\ Charles R Greathouse IV, Jun 18 2015