A280354 Numbers n such that (i) number of divisors of n equals number of divisors of digit reversal of n, (ii) sum of divisors of n equals sum of divisors of digit reversal of n, and (iii) n is not a palindrome.

1561, 1651, 5346, 6435, 157661, 166751, 301134, 321853, 358123, 431103, 507955, 511665, 517055, 537495, 539946, 550715, 559705, 566115, 576908, 594735, 649935, 729287, 765677, 776567, 782927, 809675, 834498, 894438, 896898, 898698, 905289, 982509, 1257912, 1473302

Offset

1,1

Comments

Intersection of A062895 and A085329.

Numbers n such that A000005(n) = A000005(A004086(n)), A000203(n) = A000203(A004086(n)) and A136522(n) = 0.

Links

Indranil Ghosh, Table of n, a(n) for n = 1..200

Index entries for sequences related to sums of divisors

Example

1561 is in the sequence because 1561 has 4 divisors {1, 7, 223, 1561}, 1 + 7 + 223 + 1561 = 1792 and 1651 has 4 divisors {1, 13, 127, 1651}, 1 + 13 + 127 + 1651 = 1792.

Mathematica

Select[Range[1500000], !PalindromeQ[#1] && DivisorSigma[0, #1] == DivisorSigma[0, FromDigits[Reverse[IntegerDigits[#1]]]] && DivisorSigma[1, #1] == DivisorSigma[1, FromDigits[Reverse[IntegerDigits[#1]]]] & ]

Prog

(PARI) R(n) = eval(concat(Vecrev(Str(n))));
isok(n) = n != R(n) && numdiv(n) == numdiv(R(n)) && sigma(n) == sigma(R(n));
for(n=1561, 1473302, if(isok(n), print1(n, ", "))) \\ Indranil Ghosh, Mar 06 2017

Crossrefs

Cf. A000005, A000203, A004086, A029742, A062895, A085329, A136522.

Sequence in context: A259303 A035865 A031800 * A072394 A243528 A237673

Adjacent sequences: A280351 A280352 A280353 * A280355 A280356 A280357

Keyword

nonn,base

Author

Ilya Gutkovskiy, Jan 01 2017

Status

approved