A066751 Triangular numbers whose reverse is prime.

3, 91, 136, 325, 703, 1081, 1378, 1711, 3655, 11026, 11476, 13861, 18145, 18721, 36046, 70876, 75466, 76636, 79003, 92665, 99235, 107416, 108811, 110215, 118828, 123256, 130816, 137026, 140185, 158203, 166753, 173755, 186355, 303031, 310078

Offset: 1

Author

Jason Earls, Jan 16 2002

Keywords

• easy
• nonn
• base

Links

• Harry J. Smith, Table of n, a(n) for n = 1..1000

Programs

PARI

Rev(x)= { local(d, r=0); while (x>0, d=x%10; x\=10; r=r*10 + d); return(r) } { n=0; for (m=1, 10^10, t=m*(m + 1)/2; if (t%10 && isprime(Rev(t)), write("b066751.txt", n++, " ", t); if (n==1000, return)) ) } \\ Harry J. Smith, Mar 21 2010